TechCrunch blogger Michael Arrington wrote Saturday that an iPhone-only social network, if it had the right features, "would be a huge hit with these users."

He was careful to say that while he thinks any mobile social network could be a big hit, it would require certain features such as presence detection and the ability to tell you both where your friends are and what they are up to.

He posted a solid analysis of the current situation, which we've commented on with some disdain in the past simply because of the surge in the sheer number of mobile social network sites attempting a land grab. But he feels that a network that supports a phone's built-in GPS radios and/or triangulation and that uses native software for the phone—two critical features that the iPhone is in the process of gaining—could be the lift necessary to get a mobile social network off the ground that's actually useful.