Warhammer 40k will be running at Gaelcon this year using 8th edition of the game.
The rulespack will be available mid August, the TL:DR of it is 2000 points, 3 detachments, 5 games, swanky new rule set. *Missions will be in the rulespack*
You can purchase a 40k entry ticket via this website. The ticket does NOT include Con Entry and you will have to purchase the appropriate weekend or day ticket(s). The Tournament will be held on the Saturday and Sunday of Gaelcon between 09:00 and 19:00 on Saturday and 10:30 to 17:00 on Sunday which includes registration, breaks, lunches, setup, and games.
Best and most recent information can be found here. http://w-ired.org/forum/viewtopic.php?f=5&t=5558