Google Voice on the iPhone has been something of a sore subject for me. If you need a full-recap of the whole sordid iPhone/Google Voice story see this story from December or more of our coverage. I even started a little site devoted to waiting for Google Voice on the iPhone called IsGoogleVoiceAvailableForTheiPhone.com.
It has been 6 months and 19 days since Apple claimed it had not "rejected" Google Voice but was "studying" it. During the course of Apple's "study" the company moved to purge all existing Google Voice apps from the App Store.
There were three reactions to this from developers:
Google revamped the Mobile Google Voice page so that it looks a lot nicer on the iPhone.
GV Mobile released its app for free on Cydia for those who have jailbroken iPhones.
The folks behind Voice Central went a different route. They decided to make a web app instead. I've been using it in beta for the past few months, but as of today it has been released to the public as Black Swan.
The difference between the Mobile Google Voice site from Google and Black Swan is that Black Swan is stored locally on your iPhone, like Pie Guy from Neven Mrgan of Panic.com. Riverturn calls this a "weblication," which is a fairly awful name, but apparently they aren't the first ones to use it.