Someone had a post on how to access an test menu on Android by dialing *#*#4636#*#* without hitting send. The menu has information on application use, battery usage, and an information screen that allows selecting preferences for your non-WiFi data network. The menu also has an "SMSC" option to change your text message server: but I don't think most people need to bother with that.
Networks options available on my Sprint HTC Hero: WCDMA ; GSM ; EVDO ; CDMA
Around here in Orlando, its pretty much EVDO, and my phone currently says thats what its using. Phone was set to a CDMA option: trying EVDO-only & see how that works out. Forcing the correct network setting is supposed to prolong battery life by reducing the phone's attempts to auto-seek new networks.