Thanks to a very strong recommendation from cherith, then a second from renay, I picked up "Fangirl" by Rainbow Rowell. I finished it today, and it lived up to the high expectations that had been set. A fun book, a sweet love story, and the very best fictional depiction of fandom I have ever seen. Rainbow Rowell must be in fandom. There is just no way an outsider could have written that story, could have captured the experience of being a fan, and particular of being a writer of fanfiction, without having lived it on some level. If you have any interest, I echo the call to check it out.
Next up: "Cold Steel" by Kate Elliott, which I actually got halfway through before setting it aside for "Fangirl". It's the third in a trilogy, with some of the most fantastic world building ever.