I would be willing to bet that maybe 1% of the clients listed as being T3s are really connected directly to a major internet backbone via a T3. Most are either lying about their connection speed so the client will let them make more network connections (to increase their search horizon) or may eventually dump into a T3 but have to share it with hundreds (or thousands) of others.

Based on what I've seen over the last couple weeks with LimeWire, if you're getting 10kBps on a download you should quit complaining and consider yourself lucky.