To get you your HD fix while you wait, look what I found:
Swiss gaming site 2play.ch has a video of wipEout HD gameplay up, almost 10 minutes long, untainted of any annoying comments, just simple - and remarkably clean - racing. Maybe some of you can use this to get a better image of what this game is like (or was like, this is all preview build footage). Apart from the out-of-proportion ratio of the video and a few odd distortions, this is a pretty nice video, showing off different tracks and zone mode. You can also notice the sweet sound effects of the thrusters kicking in (after the hairpin at Chenghou (though it sounds way better on 5.1), and also the nice sound change when airborn.

Interesting detail is that 2play.ch claims to know that wipEout HD is coming out mid-June. But I guess we can't believe a word they're saying there...