I believe google chat/talk is supposed to have something coming out.
Google talk supports video in Android 2.3.4 (only available on the Nexus S now). It is not clear if/when the Thunderbolt will get that upgrade or if they will back-port video support to 2.2.
In the mean time, the leaked Skype seems to be the best option, although there is another app (whose name I am forgetting right now, I'll edit if I remember) that came out in Beta last week and can do Google Chat with Video as well as a number of other IM connections. However, it only sees the back camera and not the front camera on the Thunderbolt, so I uninstalled until they get that updated (which is why I can't remember its name....)..
Alan