WPF or Windows Forms codeplex projects can be installed via clickonce now!
I kicked a 2 year old email thread with the ClickOnce team in late June to see if ClickOnce support on CodePlex was still in the plan. They said it was going to ship early July!
They announced the release yesterday:
How to deploy your codeplex project with clickonce
If you have a codeplex project (WPF or Windows Forms), please go take advantage of it. If you have a favorite project that you’d like to be able to install more easily, please ask the project owners to do it.