No, the current clients are not tested against iOS6.
I wouldn't update if you are using Jabber for iPad/iPhone and you want to keep using it without issues.
From what I know, voice/video seems to be working unstable.
The next release of the clients will provide official support for iOS 6, should be posted soon enough, so hold that upgrade for a few weeks.
if this helps, please rate
Jabber for iPad iOS6 support has been released, I updated mine on my iPad today. Are there any detailed release notes for the new version?