Are sim cards interchangeable between iPhone 3gs and blackberry?

first off i have an iphone 3gs which uses a micro-sim card. I don't have service where i live, but i have free wifi. i heard that black berries are capable of texting over wifi, i want to buy an blackberry to text over wifi. can iphone sims be used in black berries or vice versa? heard the iphone 5 was to come out soon and the torch 2 sometime soon.