Ok, Alli and I decided to investigate and I've reached a conclusion, well kinda. Alli's phone still isn't showing iPhone as an option on her list, so I don't know what's up with that. Probably has something to do with exchange?
The iPhone does NOT recognize other iPhones, it's simply defaulting to the next unused label in the list. 3.0 seems to have added iPhone as the 2nd option on the list (for some). So if you already have a mobile number stored for someone, then the next choice is "iPhone". I played around with adding to different contats with different types of numbers stored, and it always chose the first unused label on the list.
Not nearly as cool, I know.
So now the question is why don't all iPhones on 3.0 beta have iPhone listed as an option?