Let the hive mind of Engadget get that for you.
"I just switched to Sprint from Verizon about three months ago for the Pre. Then I went for the Hero about a week ago. Now, I miss my hardware keyboard and am thinking about switching to the Moment. I am still able to switch back to Verizon if I want and get the Droid when it arrives. Should I just trade up to the Moment when it comes out, see if I like it, and if not switch to the Droid? Or something else entirely? Help!"
It'll need a sim card, just like any other GSM phone. When you take it internationally, there's a setting that you hit to change it to GSM mode. And if it's anything else like the other VZW global phones, it will, by default, be locked to a Verizon Wireless/Vodafone sim card.