It is a really cool development if you're interested in portrayals of fandom within canon. If you want to get the full story, I'd recommend watching 4x18 (the one that introduces Chuck the author avatar, the fictional universe within the fictional universe, and in which the boys meet their first fan and discover slash), 5x01 (just the three-minutes of Becky scenes, in which Becky writes slash, discovers that her fandom is real, and meets Sam and Dean), and then 5x09, the convention episode.