The iPhone 3GS was only predicted to sell half a million units this weekend according to Gene Munster, an analyst for Piper Jaffray. Now it looks like Munster might have to eat his words. AT&T just announced that their 3GS pre-order sales were in the hundreds of thousands.

That's obviously not close to an exact number, but if we factor in the likely-higher Apple pre-order sales we're already looking at first weekend sales of over 500,000. And that's before we take into account any of the iPhones sold in stores this weekend. Considering some stores are already selling out, and the U.K is expecting sales 50% higher than last year's 3G release, I don't think it's at all out of the realm of possibility for the 3GS to equal or exceed the 3G in first weekend sales.

One thing is for sure; Palm has got to be feeling pretty bummed out by all this. The Pre didn't have an opening weekend even close to this, and these next couple of days are just going to affirm Apple's relative dominance in the industry. Of course, RIM and Nokia are still the leaders of the pack, but sales like this are the first step towards Apple taking their market share to the next level. When their exclusivity with AT&T ends we're going to see some very big changes in the industry.