The new update to the Android Market is out. If you dont want to wait for it to get pushed to your phone you can download it from the link at the bottom of this post. This update includes the addition of a PIN, so somebody can't just grab your phone and start buying stuff. It also includes Google's +1 button. Make sure your phone is set to allow third party apps.
3.1.3 Market APK - http://db.tt/Uvz4UGN