Near as I can tell, here's what's going on: Intel is bent on hitting the ever-so important 1GHz mark before AMD, so they are about to employ the same "accelerated launch" tactic they've used for the 800MHz Pentium III. Basically, Intel could only supply a fairly limited number of 800MHz parts, but rather than wait for volume production to ramp up before announcing the next speed grade, they shipped what they could at 800MHz rather than sit and watch AMD walk off with the MHz crown. Intel has admitted the GHz PIIIs won't hit "volume production" until the third quarter of this year.
AMD, for its part, seems to be sitting in the fabled catbird seat. The newer Athlon core is taking to higher frequencies quite well. We'll have to wait and see whether the release of 900, 950MHz and 1GHz Athlons is "accelerated" enough in response to Intel to hurt AMD's ability to deliver 1GHz chips in volume. I suspect that AMD is running a little ragged here, too, but probably less so than Intel.
Incidentally, in light of these events, I wouldn't expect a lot of room for overclocking in either manufacturers' early 1GHz chips, but you never know.
While you're ruminating on the CPU wars, have a look at this interview with "Colonel" Jerry Sanders, AMD's chairman and CEO, and genial purveyor of fried birds bathed in 11 tasty herbs and spices. For further amusement, read The Register's take on Intel trying to position the Celeron against the Athlonas if.