I run a few times a week using:

• Amphipod Micropack to carry the phone
• Motorola S9 bluetooth stereo headset
• eCoach to track my course via GPS

eCoach is great because it adds your run log to an 'ecoach' calendar in the N900's calendar app. But you have to edit each event after the fact to move it to the main N900 calendar if you want it sync'ed to your desktop...