On the new iphones they offer social network sites. I am looking for software that works with mobile phones to find friends that want sex. Is this kind of stuff out there and if it is does it work?

Apple controls software for the Iphone and Apple is the sole distributor for it via the Apple store.
As far as other phones go it depends on the manufacturer,the phones OS and the Cellphone network that the phone is on. You would have to do some careful research to find a service that works across all phones and all networks.

The way things are going, there will come(no pun) a time when you will be able to avoid the bother of finding other human beings because the phones will have sex with you.

they already vibrate, so its a start...lol

They are warm, but not wet.

However, if it is a "webapp," then Apple doesn't have any control over that.  Since what the OP is talking about some sort of social sex meeting "application," this in theory could be made into a webapp rather easily.

Many porn sites have already done this, and considering that this social app probably needs to include the 'nets, imho webapp is the way to go.  The real question is if a web proprietor thinks it is worth the time, money and effort to create such a webapp.

Personally, I'd love to see a webapp version of TER, but I'm not technical enough to accomplish such things.

Perhaps Adult Friend Finder will develop one (not that I'm a fan of AFF), just a thought.