Yes! But only Garmin so far (working on Polar now).
You need to set up an account and than link your Garmin account in the profile.
Here's the catch: Garmin only allows syncing of future activities. I can't access your past activities from your Garmin account. There's a way around it though: https://cubetrek.com/static/bulkdownload.html
I just tried a quick experiment, and it will import GPX files that are exported from Garmin. Whether it will directly pull data from Garmin Connect is a question for the dev, but a quick test drive did not reveal that functionality.
