I'm pretty sure it won't. As of now, they only have one size, and they will sell you a Cane Creek shim. It made noises until I greased the bejeezus out of it. I almost tore into my bottom bracket to go hunting for the problem until I realized what it was. (Once I greased it, it was fine.)

I posted a first-impressions thread for their suspension seatpost at the mtbr forum.