Right after announcing the release date and the price for Counter Strike: Global Offensive, a blog post at the Counter Strike Blog has been seen saying pre orders are coming soon.

Lets take a look shall we?

"The two most frequent questions we see asked dealing with access – will there be an open beta and when will pre-orders open up? For pre-orders we hope to open it up about a month before release, so roughly July 21st but that is a rough date we will firm up as we get closer. As for an open beta, where everyone can get a chance to try CS:GO, sometime between the pre-orders and release"

As this blog post says, the pre-orders for Counter Strike: Global Offensive are going to be avilable on around July 21st,  next month. Not just that, they also said, there is going to be updates with characters, audio, playing with friends, and more beta keys for the Counter Strike: Global Offensice beta players.

Blog Post