Last week's ratings of Seinfeld, the first episode after the Thursday move, showed that it was the most-watched episode ever. If I remember correctly, it got about a 27.9 share, about 10 points higher than usual, meaning about 10 million more homes than usual. No mention was made on how it ranked, but the complete list should be out today or tomorrow in the LA Times.
Another article about the NBC executive reorganization said that they were now using Seifeld as their "flagship" show, since Cheers is leaving.
John