If you have a USB Drive that may or may not be contaminated, what is the best way to retrieve data from it without reinfecting yourself?
If you want to be completely sure, mount it on a Mac or Linux box. Seriously.
For an example, see the new shortcut icon exploit, which ALL Windows machines since NT have been vulnerable to. This exploit allows arbitrary code to be executed simply when the folder is opened. No Autorun required. No manual execution required. It infects the system as soon as the folder is opened.
If you don't have a real *nix (includes Mac) box, just boot from a LiveCD. You may want to scan with Clam AntiVirus while you're at it too.
If you are using windows then disable auto-run.
How to disable autorun: http://support.microsoft.com/kb/967715