I'm posting this just in case anyone else is having this problem. I'm using VMware Fusion 1.1.2.
Problem: After a recent upgrade of my xserver-xorg packages on Debian (including xserver-xorg-input-vmmouse, which is now at 1:12.4.3-2), all single clicks were being recognized as double clicks. (xev shows each click as two ButtonPress events in quick succession.) I'm using the vmmouse driver.
Solution: I had a USB mouse defined in my xorg.conf, which is completely unnecessary with the vmmouse driver, since USB mice get handled by the host. After commenting out the following line in the ServerLayout section of xorg.conf, everything is working fine:
InputDevice "USB Mouse" "SendCoreEvents"
(The identifier "USB Mouse" might be different in your xorg.conf.)
Hope that helps, if anyone's finding this through the search function! 
-- Lea