With the new OS 4 on iPhone, the game center makes it able to link games with friends on iphones playing the same games.
What are must have apps for the iPhone?
Words with friends
Cut the rope
Hey Tell -- Great app instead of texting, it is like nextel push talk. pretty sweet
Gotta have your facebook
Tapatalk, so you can check your TW account
Kayak, to find all your flights
Now Playing, finds locals movie theatres and times
AroundMe, perfect when you need to find the closest.. anything
CheapGas, finds closest gas, and cheapest
iMapMyRide, maps out your run, or bike you just did
360, makes great panoramic photos
StarChart, great for finding constellations
SaiSuke, better calendar then the stock one
Epocrates, for any of you medical crazies....
by all means, add more to this list if you say you got a MUST HAVE