I'm using the toggle SIM (that's discussed extensively in this thread) in a Verizon Motorola Droid III. Works very well and cheaply in all of Europe, but has expensive roaming rates in Asia.
When you are on a Verizon contract, you do need to have Verizon unlock your device so it'll accept non-Verizon SIM cards. Good luck with that - I spent over an hour in a store and even longer on the phone with them to get that done....