M-Lab to help users discover whether or not they're being affected.
One of the tools M-Lab will use is Glasnost, a java applet that initiates a torrent transfer between a user's pc and the remote testing server. It compares the results to the speed of a normal transfer to see whether or not the peer-to-peer traffic is being throttled.
If you're curious about your own ISP, run the Glasnost test and see what it reports. You'll have to be patient, though - the recent news about Google coming onboard has increased traffic on the site greatly and it's having a hard time keeping up.
It's good to know that once M-Lab is online they'll have 36 Google servers in 12 locations to help run the tests.