No, Microsoft Office 2008 for Mac isn't shipping yet (it's anticipated to ship in January), but if you buy a qualifying copy of Office 2004 between November 1st, 2007 and January 14th, 2008, in the U.S. or Canada, you're entitled to a free upgrade to Office 2008 in exchange for a $7 shipping charge ($10 CDN). But, for today only, it gets better.
If you're into "Black Friday" deals, those crazy offers that crop up in the day after Thanksgiving in the U.S., the "official" start of the holiday shopping season, you'll love this one: if you're in the U.S., and you buy your qualifying copy of Microsoft Office 2004 on Friday, November 23rd, you'll get a
The says even the inexpensive Student & Teacher Edition qualifies for the rebate and the free upgrade, turning the $125 price for that version (available to full- or part-time students, parents of minor students, home schooled students, and full- or part-time faculty or staff of an accredited educational institution) at Amazon.com into a cool 
The current deal that extends until mid-January is even better than the upgrade offer which promised an upgrade for $10 shipping to a comparable edition of Office 2008 to what you'd purchased from the Office 2004 product line. Now, Microsoft says, everyone will get the Office 2008 Special Media Edition, no matter which version of Office 2004 is purchased.
If you're not in the U.S. or Canada, all is not necessarily lost. We're told that different Microsoft regions have different offers available. Check for details.