tetragrammaton's right. There is no built-in way to do this.
I think there's a utility that allows you to send vCards floating around on the internet somewhere, though.
Best way is to just go to your contact, select the number, copy, and then paste it into your sms. Most (not-so-smart) phones will recognize the number automatically.
Have anyone noticed that the Windows Mobile Phone Edition just 'swallows' certain types of smses?
Nokia Business Cards and Picture Messages never reach me, and I also never get any indication that the phone ever encoutered them, either. :shock: