Anyone who has visited Blizzard Entertainment's official website knows the release date of Starcraft 2. How do we know that the set release date is reliable? Blizzard has a history of delaying their products.
Whilst I agree that Blizzard does delay, and is, in fact, near notorious for that, I'd say that the fact that they waited literally years to even conjecture one adds validity. While I'm not saying that added delay is impossible, I just feel that, at this point, you're perfectly safe in pre-ordering it and expecting it to be playing it in a few months time.
The playability of the beta is a testament to how polished StarCraft 2 already is, and a July 27 release date seems completely viable. Of course, if a game needs to be delayed for quality than it needs to be delayed!
They don't change release dates that have been officially announced unless something horrible happens as they will have scheduled with suppliers, manufactures and retail how/when they're going to print 4 million copies and send them out to everyone.
One of my thoughts on the manner is that I was hoping to buy a copy of the Starcraft II Collector's Edition for my little brother for his birthday when I come home on leave (vacation) from the United States Navy in July of this year. I haven't placed a leave request chit yet and haven't decided whether to take the first or second half of July off from my usual duties.
The most important things that need to be fixed are performance and compatibility issues as well as Battle.net stability. They should have that fixed by July unless they really are using monkeys to code.
Blizzard did say they will have a day zero patch for SC2 somewhere. As you'll have to download a patch before you can play it. That is just for all the fixes made in the window of time before the release date but after the discs are shipped to the stores.
And I have a question that is more relevant to this forum than Starcraft II itself. I've posted two posts in the Lounge, so why am I still waiting for them to appear? One of them is a thread about the oil spill in the Gulf of Mexico and the other is a reply to a thread about Facebook.