Making his first appearance on television since his much-lauded speech on race relations, Sen. Barack Obama helped push ratings for ABC's Nightline over those for The Tonight Show With Jay Leno and The Late Show With David Letterman Tuesday night. Nightline drew a 4.0 rating and a 9 share versus a 3.9/10 for Tonight and a 2.5/6 for Late Show, according to Nielsen Research. Among the key demographic group of adults 25-54, Nightline (2.1/8) held a 31-percent margin of victory over Leno (1.6/7) and a 200-percent margin over Letterman (0.7/3).