+1, and also uses zrtp

nice. it requires a 3rd party FB, Google, AIM, ICQ, ippi, iptel or MSN account but it says they optionally use OTR.

Not 100% secure IMHO but close. Why do they have to rely on a 3rd party for authentication? This still gives (at least, if you manually enable OTR encryption) the connection data to the service providers.

You can get away with any old XMPP account, provided that your contacts are either on the same network or your network and theirs are federated.

This used to be the case with GTalk, but sadly isn't anymore.

Needs to be quality on mobile too.

It's all standard communication protocols. You can use any mobile client you want.