The Wireless Web - Is it Secure?

This curious member of Clan Anonymous Coward asks: "I really know very little about the technical details of Sprint's Wireless Web network, AT&T's PocketNet service, and others like them. I'm wondering whether the encryption over the airwaves for these things is any good ('powered by RSA') and properly implemented." This is a decent question on what might turn out to be the next generation of communications services.