I just installed the v3.00 firmware upgrade for the Garmin Forerunner 301. In addition to some bug fixes, the major improvement in this release is the addition of support for MultiSport.

With this upgrade, you can configure the Forerunner for events like triathlons. You specify the order and type (run, bike, other) of each leg. After you start the event, you hit the "Lap" button to transition from one leg to the next. You can even have it record your transition times (hit the "Lap" button at the start of the transition and again at the end). I used this feature yesterday on my brick (run, bike, run) workout. Worked like a charm!

Click here for the upgrade. Click here for the updated user guide (Owner's Manual Rev. D)
Click here for a page describing the bug fixes and previous firmware upgrades. Good accessories too.