Some searches from the world wide web:
http://forums.bicycling.com/eve/foru...7/m/3731042216

http://cyclingexperiences.com/2009/0...t-update-0302/

Examples with a non-barometric device
http://gpsrunner.blogspot.com/2009/0...orrection.html
http://getsatisfaction.com/garmin/to...a_doesnt_match

Quote from Garmin at some point in time (Iforget when):
Garmin Connect is using a different methodology to smooth elevation gain/loss compared to MotionBased. As a result, especially for Forerunner devices, the elevation gain/loss numbers will be inflated. We are still working on our smoothing algorithm and intend to run this across all activities at Garmin Connect in the future to more accurately reflect the actual gain/loss.
Garmin Connect does not support weather at this time. We plan on introducing this feature at Garmin Connect. When we do, it will run against all past, present, and future activities at Garmin Connect.

I lurves me Sporttracks.