The upcoming Children's/YA con that guitarbabe has heard about may be the one I've gone to the past two years in March. It is not at BYU--it's at UVSC. It is called the Forum on Children's Literature, and it is for teachers, writers, illustrators, and librarians. The link is
here. I have attended twice and found it to be very good. If you are a student, it is the best deal around--I think it's like only $35 for both days, and you get fed. If you're not, it's a little over $100 I believe. Still probably worth it--because you get to meet an editor and local writers, plus the special guests--but still not as good of a deal as when you're a student (which is why I got to go the last two years no problem).
I found this event to be more organized and helpful than Nasvic (the con we went to last September). The nice thing is that they had an editor from a good Children's/YA press each year--Candlewick two years ago and I think HarperCollins last year, I'd have to check my notes--and both times the editors said, "Since you are at this con, anything you send to me you can mark as 'requested material'"--and they said this whether you talked to them or not in person, they just announced it to everyone. And the break-out classes are NOT panels, so people actually plan and put together good, helpful information. I recommend it.
If you can only do one, though, do BYU's YA Conference in the summer--the writing one. I went two years ago, and it was very good. Some people on the board went last year and didn't find the workshopping part as helpful, but you still get to meet two editors and an agent, and the afternoon break-out classes have lots of information usually. Besides, you never know when Chris Crowe might perform Britney Spears again--he did it two years ago when I went! Definitely worth the $400.