fring is out, see http://phobos.apple.com/WebObjects/M...290948830&mt=8
fring is a VoIP (Voice over Internet Protocol) client. It means you can make phone calls over the internet. The great thing that distinguishes fring from Truphone and other competitors is: fring connects to almost any service where you already have an account. Your Skype account, or any of your SIP-based accounts, will work with fring.
Disadvantages: it used to be a jailbreak app, but it's now in Apple's AppStore -- so it can't run in the background (you can't wait to be called) and it won't run over the 3G (or EDGE/GMTS) network.
What are your experiences with it?