Cycler by Laurel McLaughlin

On a YA panel at a local SF con last year, Cory Doctorow mentioned a book about a girl who instead of getting her period, becomes a boy for four days each month. I was intrigued. It's called Cycler by Lauren McLaughlin and I just finished reading it this afternoon. 

I loved it. With humor and a keen eye for the pressures of teenage life, McLaughlin takes us on an exploration of gender construction and identity that I for one will not soon forget.  Fun fun!

And it turns out there's a sequel!  You can bet I'll be running out to buy (re)Cycler very soon!