foreach(SPContentType listType in list.ContentTypes)

listType.Parent is a valid content type which is a site content type, but it is null for the Workflow History list content type on the Workflow History list.

Note: The Workflow History list being hidden, one cannot navigate to it via View All Site Content. But if one knows its GUID, one can navigate to it via ~/_layouts/listedit.aspx?List=%7B123456%7D, where 123456 stands for the actual GUID.

Background
I wanted to quickly make a copy of a publishing site collection that I had been working on (for a colleague), and did the following.

First, as stated above, the site I wanted a copy of was a SP Publishing Site. I knew from preious experience that one is unable to save a publishing site as a site template (it's not supported by Microsoft for good (although unfortunate) reason).

That being said, I moved forward with an unsupported workaround (FYI, this was in a development environment). I deactivated both the Site Collection and Site/Web Publishing Features ([Office SharePoint Server Publishing Infrastructure], and [Office SharePoint Server Publishing] respectively). Once deactivated I had the menu option "Save site as template" available to me (under Site Actions >> Look and Feel ), and was able to successfully save the site as a site template.

Upon my attempt to reactivate the site collection publishing feature (that I had deactivated in the previous step) I ran into the following exception:

Exception occurred. (Exception from HRESULT: 0x80020009 (DISP_E_EXCEPTION)) 

Solution
To resolve this problem I ran the following stsadm commands (replacing "URL" with the actual URL of the Site Collection) - which I found on a Technet forum, posted by Chris Winebarger.

stsadm -o activatefeature -filename publishing\feature.xml -url http://URL -force
stsadm -o activatefeature -filename publishingresources\feature.xml -url http://URL -force
stsadm -o activatefeature -filename publishingSite\feature.xml -url http://URL -force
stsadm -o activatefeature -filename publishingweb\feature.xml -url http://URL -force
stsadm -o activatefeature -filename publishinglayouts\feature.xml -url http://URL -force
stsadm -o activatefeature -filename navigation\feature.xml -url http://URL -force

All was then back to normal.

Reference:
Chris Winebarger's post on a SharePoint Technet Forum 
http://social.technet.microsoft.com/Forums/en/sharepointadmin/thread/13da092f-8c6f-44c8-a99b-140e277c8d55

OOB Sharepoint Link Lists do not provide you the option to have a links open in a new window. The following steps and script will allow for such functionality.

Steps:

1. Add a Content Editor Web Part (CEWP) to the page where the linked list web part is located.
2. Select Modify Shared Web Part on the newly added CEWP
3. Now click the "Source Editor..." button that is now present and insert the following script (Note, you can choose to hide the title and chrome of this web part so that it is, in-effect, hidden from the end-user):

   <script language="JavaScript">
   _spBodyOnLoadFunctionNames.push("rewriteLinks");
           
   function rewriteLinks() {
     //create an array to store all
     var anchors = document.getElementsByTagName("a");
               
     //loop through the array
     for (var x=0; x<anchors.length; x++) {
       //check to see if the current anchor element contain #openinnewwindow
       if (anchors[x].outerHTML.indexOf('#openinnewwindow')>0) {
         //add the [target] attribute and rewrite the [href] attribute
         anchors[x].target = "_blank";
         anchors[x].href = anchors[x].href.replace(/#openinnewwindow/,'');
       }
     }
   }
   </script>
   

4. Next, add a new link to the linked list and append the following text to the end of your URL "#openinnewwindow" (e.g. http://www.google.com#openinnewwindow ).
5. Finally, click on your link and it will now open in a new window.

An Error message will be displayed that states:
"The Office SharePoint Server Publishing Infrastructure feature must be activated at the site collection level before the Publishing feature can be activated."

The site that you have attempted to create will still be viewable from the View All Site Content link (then look under Sites and Workspaces) but will generate a 404 error if you attempt to browse to the root (either by clicking the link under view all site content, or manually browsing to the site name you've chosen). This is because the site was created, but was not given a default.aspx page. I've found that the only way to delete this broken site, is to browse manually to the site's settings page (which does exist).

This can be navigated to like such:

http(s)://portal_url/site_collection_name/broken_site_name/_layouts/settings.aspx

UPDATE:

Apparently, stsadm does not create this broken site.

#1) SPFeature.Add ignores access denied failure

My major problem with SPFeatureCollection.Add is that it does not report failure due to access denied.

In the case of attempting to add a site collection feature, when the current user is not a site collection administrator, SPFeatureCollection.Add will create a new SPFeature object in the collection and return it, although the feature has not actually been activated on the site collection. I expected to be able to work around this by creating a new SPSite object (pointing to the same site collection) and checking its features collection, but no -- the new feature appears there as well.

For this reason, SharePoint Solution Installer does not report activation failures -- because they seem undetectable at the API level.

#2) SPFeatureCollection Add & Remove act differently than GUI if feature receiver not found

My second problem with SPFeatureCollection, Add and Remove both, is that they succeed silently in the face of feature receiver misconfiguration. From the GUI, activating or deactivating a feature missing its feature receiver assembly will fail, with a fairly descriptive error message (if custom errors are disabled). However, SPFeatureCollection Add and Remove will both actually succeed in this case.

This can be useful; it is a workaround to deactivate a feature which cannot be deactivated from the GUI.