As a vegetarian and a scientist (albeit a physicist), the prospect of lab-grown meat has me incredibly excited. However, rather than discuss the moral implications, I'd like to address something not mentioned in the article.
PETA won't really accomplish anything with this, nor does it plan to. The process of research and development for this will cost far more than a million, but even if it didn't, this is not the phase in which such a prize would be useful. It is still necessary to learn how to grow potentially edible meats, to learn how to produce the right texture and flavor, to learn how to produce in great quantities, to learn how to minimize cost of that production, to obtain the legal rights to sell such meat, and to raise public demand to the point where it becomes commercially viable (which involves somehow convincing a predominantly bio-Luddite population that this isn't a bad thing). PETA has set an expiration date on the prize of July in 2012. Just four years to do all that? Nigh impossible on scientific timetables, where grant money can take the better part of a year to acquire in itself.
It's a great gesture, and it's great to see PETA adopting a progressive approach in favor of its standard polemics, it's nothing more than a publicity stunt or a calculated PR move.