One of the perks of being a member of the American Homebrewers Association (AHA) is the opportunity to buy tickets to the Great American Beer Festival (GABF) before they go on sale to the general public. The members-only pre-sale starts at 10:00am MDT on Tuesday, June 28th and includes the opportunity to buy tickets to the Farm to Market Pavillion as well. Members should have received an email message with instructions and a link to purchase tickets. If you're not currently a member, you can still quality for the pre-sales event by joining the AHA before June 26th (click here for membership info and benefits). The remainder of the tickets will go on sale to the general public on Thursday, June 30th.
Considering the GABF has sold out for the past four years (and did it earlier then ever last year), I wouldn't hold off on buying tickets if you're thinking about attending. The session that typically sells out first is the members-only session on Saturday afternoon which is when the winners of the competition are announced. I think the Thursday evening session is the best as all the beer is available and most of the brewers are usually around and still energetic. And if you are going, don't forget to pick up a ticket for the Denver Rare Beer Tasting as well.