If you've ever been to a convention and seen all of that wonderful swag, you've also seen the lines to procure that wonderful swag. It's annoying to wait in a line for an hour just to buy a T-shirt that you can only get at that venue.
Blizzard is bypassing this issue by allowing anyone who has purchased a BlizzCon ticket to grab those unique merchandise items ahead of time and online. No fighting over the last murloc head can cozy or Raynor onesie for your child, just simple online transactions with the goods being shipped directly to your home.
This is only for people who have actual tickets to the event. Anyone with a virtual ticket will have to wait until the 13th to get in on their own 48-hour sale. If you don't fall into either of those groups and still want to get in on the swag, then you need to go buy your virtual ticket before 11:50 p.m. Pacific on Oct. 10 to qualify for the sale or you're out of luck.