
Signing in with Live ID
According to the CodePlex blog, support for Windows Live ID was the second most requested feature.

CodePlex login with LiveID
You do still need a CodePlex account, but once the two are connected through your first time logging in with Windows LiveID you don't have to use it again. Also, your Windows Live ID cannot be used to log into Mercurial or TFS (both need Active Directory credentials).
Serving Up Ads
You can also now place ads on your project pages using The Lounge, an advertising network for publishers focused on Microsoft technologies. If you choose to include ads on your project pages, all the ad revenue is yours (and they have set up some processes that will make the ads stand out) or you can donate the money to Habitat for Humanity.

CodePlex with Ads via The Lounge
Additional Changes
Live ID and Ads may have been the big changes to CodePlex, but there are a few additional changes as well, including:
- Search Term Suggestion Pop up
- Syntax Highlighting for PowerShell scripts
- Updates to Mercurial hosting
What's Next?
There are a lot of other requests for improvements in the Issue Tracker including support for ClickOnce, adding a tab for screenshots and allowing co-ordinators the ability to delete wiki pages.
Not sure what will come next, but improvements are always a good thing, no matter what they are.