Nimbuzz just released their new iPhone version of Nimbuzz which also supports 3G VoIP "dial up" calling and can turn the iPod touch into an iPhone. The old version was just released into the Apple iTunes store in November, so Nimbuzz is cranking out new version pretty quickly!The new version features a full dial-pad, and the ability to make VoIP calls to PSTN numbers using SkypeOut, as well as via their 10 VoIP partners including Gizmo5, Vyke, sipgate and A1 by leveraging SIP. You can now add individual buddies from AIM, Google Talk, Windows Live Messenger (MSN), MySpace, Yahoo!, and Nimbuzz.
If Wi-Fi is unavailable you can make VoIP calls to Nimbuzz buddies using what Nimbuzz calls "Dial-Up VoIP", which is available in over 50 countries.
Dial-Up VoIP simply means that Nimbuzz dials a local access number that your iPhone dials and then Nimbuzz's VoIP servers terminate the call. Jajah, and others have this feature as well. fring also has a good app for the iPhone.
According to the Nimbuzz blog post, "We are experimenting with Twitter, and you can post to Twitter via the Personal Message feature! Try it. Your comments are always welcome, so please feel free to give feedback." Wow! Twitter integration with a VoIP app. Gotta love it! 
Fixes:
• Facebook names are displayed
• Mobile Me usernames with a dot are now supported
• Improved stability
Technorati
Del.icio.us
Slashdot
Digg
twitter
Why is this so great. A voip software that can make calls over wi-fi. Also, there is no way AT&T is going to allow VOIP calls over their network. The AT&T acceptable policy does not allow it.
This is infact a great news. Nimbuzz will be more significant now since it started providing support for iphone along with a variety of messengers support.
Nimbuzz come up with the best app,and also very cheap calling rates, though this app is already introduced by jajah and truphone and Vopium is going to launched it soon, but I think is very good for VoIP industry.