ICANN hasn't let VeriSign release the service yet, but registrars are starting to take pre-orders. What's interesting is to see how the registrars are going to package and price it.
Network Solutions is taking preorders
here and it's pretty straightforward: one pre-order per domain name on a first come, first served basis. $39 if you get the WLS on your name, which includes the first year's registration in your name if the name deletes. (Lots of ifs...)
Enom is taking preoders
here, but it's not purely first come, first serve. They have this auction system set up where you're basically bidding to see who will pay the most to get the rights to the pre-order. Cost is $35 if you're the only preorder or $50+ to start the bidding. After being the most vocal critic against WLS, eNom has apparently decided to milk it for all it's worth.
If you
really want the WLS rights to a name and you think you're not the only one, then theoretically you could put in preorders at all the different registrars that are offering the service. So in essence, the preorder environment is a lot like the current backorder world. No guarantees. But after it's launched, things get a lot simpler. Either the rights will be available, or they won't.