Yep, it's a bunch of boothes set up with representatives from each school. Sometimes the rep is someone who can make admissions decisions, and you can make a good impression. Sometimes it's an alumni (esp. for out-of state schools) who just sits in to answer questions about the program. I think it's worth going if you are doing research, and just in case there's someone there who you can impress. You can pick up applications and catalogs, at a minimum. The DC one should be pretty huge and well-represented, so I'd say it's worth your time!