With Empathy connected to many different accounts, contact groups easily become unwieldy. This is because different services have very different ideas of what contact groups are, and they really don't cooperate:

 - Facebook contact groups correspond to friend lists, which are used more as a privacy control mechanism than a way to categorize people.
 - Facebook's default contact group is "Facebook Friends"
 - Facebook's default contact group ends up with a lot of contacts unless users are especially picky. The chat interface on Facebook.com makes such pickiness unnecessary, as contact groups are not visible.
 - Android creates a Google Talk contact group called "Starred in Android."
 - Telepathy doesn't seem to handle changing contact groups very well.

This becomes especially troublesome with meta-contacts. I have a meta-contact that is regularly listed three times because he appears in Facebook Friends, Starred in Android and Personal. If I starred this contact in Empathy, he would appear four times.

In other words, contact groups can hinder more than they help. So, for these situations, it would be helpful to include an option to completely ignore contact groups and display contacts in a flat list. It would be nice if the Favourite Contacts feature continued to work in this case.