It's another 80's reboot like Karate Kid due out in 2010. It's of interest as the Red menace in the 2010 version will be China. It's due out for this Thanksgiving.

Here's the official site, which is unimpressive so far.

Here's an unofficial site, which includes such gems as the Australian Red Dawn. I'm told the villains will be Asian there too. Check it out.
Tomorrow When The War Began (2010) Official Trailer (with cast info)