With information regarding ESWC being on a something of a drip feed, many will be comforted to see the rulebooks for each tournament being published in .pdf format on their homepage. And yes, Counter-Strike: Source is included.
While it still isn't exactly clear who will be going, who will be holding qualifiers and how many teams will make it to the CS:S component of the event, at least we know such juicy titbits such as "Counter-Strike: Source will have knife rounds in order to decide sides."
So far the rules for Counter-Strike 1.6, Counter-Strike: Source, Warcraft 3, Defence of the Ancients and Starcraft 2 have been published. FIFA and Trackmania will follow shortly.
If you're interested in reading up on the rules ahead of qualifiers that may or may not be happening, you can do so
by following this link.