Sorry to jack the thread Justin but..... and I know you know this but others may not.
There is no "the GSM network", GSM is a transmission standard (like FM) that Cingular and T-Mobile use on their networks (as do most of the rest of the world) but they maintain seperate networks and have built (or acquired) them differently in different areas so GSM coverage is very different in different regions of the country. Cingular is still in the process of converting their network from TDMA to GSM and even after acquiring the AT&T GSM net their coverage area for GSM is changing daily. Since there's no such thing as roaming fees anymore there's little difference in theory but I had nothing but trouble trying to roam on the AT&T (now part of Cingular net) with a T-Mobile phone. Anyone looking at these two should check their "normal" calling area and see which has the best coverage where they go, in fact check any provider that's an option if coverage matters to you at all. I suggest getting a prepaid phone from them and using it for a month or two before signing on the line, cheap to obtain and easy to ditch if you don't like them.
As to interchanging phones you want to be careful advising people that they can do this since most US providers (including the GSM ones) still "lock" their phones to their network. You can't switch the SIM to another phone unless the other phone is "unlocked" from it's orginal network. Most people don't know this and many have bought an (expensive?) eBay phone only to find out it's locked to the other guys' net, won't accept their SIM, and the providers won't give them an unlock code because they aren't customers. Then it costs them more money and/or time to get it unlocked.
And then there are the CDMA providers........ I think Craig is right about the dinosaur thing but the "battle" is far from over. If a CDMA provider (Sprint and Verizon are the biggies) offers the best plan and coverage for you right now and you can live with the voice quality go for it. They won't be shutting down before you're ready for a new phone or plan.
Now back to the originally scheduled thread....
Sometimes, we just need to remember what the rules of life really are:
You only need two tools: WD-40 and Duct Tape. If it doesn't move and should, use the WD-40. If it shouldn't move and does, use the duct tape.