I don't know about checking the /proc things, but if you're running Ubuntu Jaunty 9.04 64 bit and haven't added the boot parameter, then VDSO is enabled. The instructions on the wiki page mention how to disable it, although personally I used kgrubeditor for point-and-clickiness.

One way to check whether it's enabled is to try and login to scratchbox and see if you get the error message mentioned on the wiki page.