From Watch with Kristin, E!Online: "Supernatural: 3.7 million viewers. The CW's demon-hunting pretty boys did well for themselves, chasing down 400,000 more viewers."
According to TV.com, "At 9 p.m., the CSI rerun earned a 5.0, with Fox close behind at 4.9. ABC's Grey's repeat scored a 4.5, while NBC's Deal or No Deal nabbed a 3.5. The CW's Supernatural spooked a 1.7." and "Overall, Fox earned a 4.5 rating/12 share in 18 to 49s, with 14.6 million total average viewers; ABC, 4.1/11, 11.8 million; CBS, 4/11, 13.2 million; NBC, 3/8, 8.4 million; CW, 1.9/5, 4.2 million."
The Futon Critic reports continuty in week-to-week gains (this week, Supernatural held 90% of Smallville's women 18-34 audience and 100% of its women 18-49 audience), and according to an interview with Dawn Ostroff, the CW's entertainment president, "Last week Supernatural retained 94 percent of the women, 18 to 34, who were watching Smallville, which is great when you think about the competition Thursday at 9 — CSI and Grey's Anatomy." (The Biz, TV Guide).
Also, starting Nov. 30, Supernatural will be up againstGrey's Anatomy, The O.C., CSI and the returning Scrubs (source: Ausiello Report, TV Guide).