I've tried several, and so far I can't get one that will just work with my work jabber + conferencing (jabber 'rooms'). They all seem mostly clunky. Does anyone have a rec that has worked well for them for me to try?
I'm using Trillian for Android. As far as I know it's still in beta, but worked well for me so far. Though I did't use it in any extreme situations yet. Oh, and it doesn't handle calls yet.
Edit: It's out of beta... and now you have to pay for it. If you don't like that, or don't have the money (or you can't buy apps from the Market like me) you should use something else.
I'm using IM Plus, which was the only thing I could get to work with our Jabber server. It's been very solid for me and they have a decent forum community, too. FWIW, I liked it enough to pay the $5 for it.
Xabber supports MUC/conferencing
Jabiru is another one.