I recently bought a Sanyo 26" LCD HDTV with one of those QAM tuners. When I've got the cable line hooked directly to the "Digital Antenna In" 75 ohm CATV input, Here's what I get for local HD:
Local access on 74-1, 74-2 and 74-3 (Public, Gov't and ARTS), NECN, TBS, HSN, QVC, C-Span 1 and 2, the local analogs including WRDM-LP (TEL) channel 50 Hartford, CN 8, Shop At Home, CT-N (kinda like a local C-Span?), EWTN, BET, NBC Weather Plus, Fuse and an NBA League Pass Info Channel. Besides that, I also got WTXX-DT (WB), WEDH-DT (PBS) [which is cable only], WVIT-DT (NBC), WFSB-DT (CBS) and WTIC-DT (FOX). No HD came in for I/PAX or UPN. As for the locals I did get in HD, it was only the primary channel for each (3-1 CBS, 8-1 ABC, etc.). NBC Weather Plus is technically 30-2 but Comcast already carries that separately anyway. What was strange was that I seemed to be getting an On Demand movie or two as the feed went to nothing the second the movie was over and it didn't match any listiings at tvguide.com or the channel guide on my converter in the other room. Strange!