Hi,
"Nightwatch" is also repeated late on Saturday night, on FilmFour. Just to clarify a few things, though:
1 - The "... Watch" series is not a trilogy: there are 4 books by Sergei Lukyanenko, and (eventually) 4 films in the series - "Night Watch", "Day Watch", "Twilight Watch" and "Dawn Watch", in that order! "Dawn Watch" is due out in hardback towards the end of the year, here in the UK.
2 - The films are all being released by 20th Century Fox in the UK and US, but UK cinemagoers will only find the films getting a very, very limited theatrical release in London, due to the cost of creating an English-subtitled print with the special interactive subtitles. (If you've seen "Night Watch" on DVD or on Film4, you'll know what I mean!) As such, though "Day Watch" has been given a BBFC 15 certificate (with a 132 minute running time), this was done back in March 2007. The BBFC site does say that the film is expected to open theatrically on 5th October 2007, but probably only for a short time in London. I expect that the DVD will come out in the UK before the end of the year, to coincide with the hardback publication of volume 4 of the book series.
3 - All 4 films will be directed by the same man, Timur Bekmambetov, with the main character being played by the same cast. (This will make a real difference and improvement, for continuity purposes over the entire series!)
4 - As far as I know, there is no actual difference between "Night Watch" the Russian version, and "Night Watch" the English-language subtitled version, other than the audio and subtitles. I couldn't see the point of Fox including the original Russian version, and then two English versions of the film on DVD, when the only difference between the two English versions, are that one uses the special interactive subtitles, and the other utilises standard subtitles. But if anyone can explain otherwise, then please let me know.
5 - ProjectorDreams - the reason Amazon has the "Day Watch" DVD listed on their site, is because it is a Russian-language only DVD release!

There are no English-audio tracks, nor any English subtitles included, and it's also a Region 5 PAL encoded DVD, with no extras! I'd wait for an official UK release.
Pooch