Hey Doodle,
It's possible alright to do that. Generally openSUSE wouldn't be the first choice because of its size and the extra configuration required. However there is a HOWTO. It is written for 10.3 but I assume it would work for 11.
Live USB stick - openSUSE
More popular options are Knoppix or Slax. Slax is only 190MB in size and has a full KDE environment. It is very fast and is modular so you can add extra applications after.
Also when you run a USB system generally they either run fresh every boot or allow you to manually save sessions. The latest Slax has gone one further and actually remembers all of your settings as if it was an installed system. I highly recommend checking it out if you don't go for the full openSUSE install.