Isn't the Nexus One Google Voice enabled?

Enabling IMAP won't do a bit of good if it's not open through the firewall. Opening the hole in the firewall requires change control documentation for SOX purposes, good governance, and security sanity, and no change request gets approved without business justification. YMMV.

I don't think this is so revolutionary for existing Pidgin users. I've had the Facebook plugin (http://code.google.com/p/pidgin-facebookchat) for Pidgin for a while now. What reasons are there to switch from this to XMPP?

I've never used Firefox Mobile, and probably won't for a long time. Your insistence that Safari and Opera are complete web browsers, however, is laughable. Mobile Safari is by no means a 'complete' browser: no support for add-ons, missing Flash support, etc. Opera Mini isn't even a true web browser - it's a redisplay app like Skyfire, and neither of them are all that great. I can't talk about Netfront because I've not used it either. Got a download link?

You can get it here: http://www.mozilla.com/en-US/m/

I hate to burst your bubble, but Safari on the iPhone/iPod Touch is not a 'full mobile browser'.