Found this little gem while trying to prevent selection behind the jQuery.treeview controll.
onselectstart="return false;" style="-moz-user-select: none;"
This worked for me on Chrome, IE 8, and FireFox 3.6.
Found this tidbit here.
Update: 2010-07-05 – Found this interesting extension to jQuery also. Note the replies also as they may be of use.