The 9800Gtx has been available in retail stores in Australia for a week.
It's about $375 in a cheap shop - thats a lot less than 200 UK pounds. Performance is better than the 8800GTX, but not a lot better. It's 512mb memory is blamed for it not being quicker in some games.
Word is that the replacement to the 9800GTX, due by Xmas, is a LOT quicker.