thank you for the kind words... we got a lot of enhancements and features on the way

stay tuned for more cool stuff.
Hi buddy, 12hours of using your app and im loving it so much!
in just one night i've saved about £4 in international texts.
why did no one tell me about this app earlier! Anyway i hope your servers can cope, i've got 17people signed up and they've all signed up a few people too. I see big things for this app, even if it is just in my circle of friends who all have a blackberry or iphone! I think you should charge about £9.99 for this app - everyone would save £10 in less than a month!
On your website,
www.whatsapp.com - you should create a forum with a feedback, feature requests and problems page. This way others can see what is happening with the app and you wont keep getting people like me taking over other people's threads.
Good luck with your development and if you ever need a tester, i have my old iPhone 3G knocking about so i will happily help you out.
Further feedback - when the iPhone switches from wifi to 3G, the app does not automatically restore the connection to the server. For example, a friend messages me "hello" while im on 3G, i open the app and read the message, the iPhone switches to wifi, i type my reply to the message "hello Matt" and hit send, the app says connection error and that im not connected to the internet - even though im on wifi. Quitting the app and reopening, and it connects again and i can send my message (loving that it saves the message in the reply field). It's a minor problem, but could get annoying if someone was moving around a house where the wifi connection was weak and kept switching between 3G and wifi.
keep up the good work!!