So Android's here at last and the first thing that I wanted to know was - Are there any SIP clients already available?  I've got one listed below to check out but I'd just like to point out that although the iPhone is simply the 'coolest' phone around at the moment, I think that Android is going to be it's biggest challenge due to it's complete open-ness... There are soooo many programmers out there wanting the opportunity to write apps for Android it's going to be interesting to see if the Geeks can topple the Cool guys...

http://www.mjsip.org/
http://tecknolojia.blogspot.com/2008/04/sip-user-agent-for-android.html