I understand octazen does that, but it has a nicer interface, and has been tested before, I dont think having only Gmail/Yahoo will make anyone use it, I know you want people to buy the paid version, but then you should have just made the demo and a paid version. But the free version is mostly useless without at least windows live.
One more thing, you should really really work on the interface, the icons are so confusing, align them together and improve the quality of the images
You should have made a promotional discount or something, because as long as its more expensive than older tested software, I doubt a lot of people will get it, as octazen wont stand around watching you add features
You made me now think again about octazen because of the features lack, but still yours is more expensive

I could integrate OpenInviter tho its so much pain...
Good luck anyways