Tested Skype versions
- Skype 5.5.0.124
- Skype 6.0.59.126

Supported features:
- sending Instant Messages to one or more users (groupchat)
- making calls with one or more users
- making video call with one user
- showing status of users in team member node of Team Explorer

Limitations:
- refreshing user status in team explorer is not possible at the moment (maybe a Power Tools bug)
- Messenger provider is showing same behaviour
- workaround: push the team explorer refresh button
- sometimes users are shown twice at the TFS Power Tools 2010 Add users dialog

FAQ
http://tfscollab.codeplex.com/wikipage?title=Skype%20Provider%20V2&referringTitle=Documentation

Supported Power Tools Version
TFS Power Tools 2010