Only Verizon Wireless has any phone labeled "Droid". But all networks currently support phones that run the Android Operating system. Droid is a Trademarked name by George Lucas (Star Wars) and as such Verizon Wireless pays out the ass to call all their android devices "droids". There is the Droid, Droid Eris, Droid Incredible, Droid X, Droid 2 (future), Droid Pro (future) currently. All those are Verizon Wireless phones.
Other Carriers have android phones like the G1, Hero, Backflip, EVO, Galaxy, etc...
Hope this helps.