Just went through the source link in Steve's post. There is a description as how to get the early bird discount prices of $49 and $99, and the chance to win some coupon codes!
"It's not quite that simple, though: starting tomorrow, June 26, you'll be able to pre-order upgrades at much cheaper prices -- $49.99 for Home Premium and $99.99 for Professional, just as we'd heard -- but pre-orders will be strictly limited in number and are expected to sell out quickly. Obviously we'd prefer it if final pricing was $49 and $99 for everyone, but it's not a bad start, especially since participating manufacturers will be offering cheap / free upgrades to 7 on new computers sold after tomorrow with Vista as well.
Oh, and don't you worry about scoring a place in line, because we're here to help: later today we'll be giving away 100 codes that guarantee a pre-order spot at the discounted prices, and you'll be able to share the code with two friends. You'll have to act fast, though -- the codes will only be valid for 48 hours. Keep your eyes peeled for our recession antidote post around noon EST, and get your clicky-fingers ready.
Update: Looks lke we've got our first participating manufacturer -- HP machines sold after tomorrow will receive free upgrades to 7, and we're hearing Sony will announce a similar offer soon. We'll be keeping a full list of announcements as the day goes on, check back later for more."
Go get it gals/guys! Hurry!