I haven't told you about CodePlex project I have started more than a year ago.
The goal of this project is to fulfill the missing feature of full branch history of items in TFS explorer GUI.
Why do I tell you about it?
Because it's going to become obsolete when Rosario comes:
Microsoft has released History Improvements Feature Specification document.
This feature actually complete all the missing functionality in TS 2005.
There are some more Feature Specification docs available currently:
if you have comments or questions on those docs, the TFS team want you to send them in Technology Area - Team Foundation Server Forum.
Hope it will help you get ready to Rosario.