Need information on dual sims .

Hi i was wondering if it is possible to have 2 simcards in my iPhone 3GS?
Anybody know or has tried this?

Hey i had the same idea and found the product for this.
I am using Hypercard for iPhone 3G/3GS from a company called 2-phones-in-1
The card works fine. I can select the sim under sim applications and the sim change is really fast.
And the best is i stll have full 3G signal.