Hi there,
I couldn't wait any longer either, and just bought a new iBook two days ago.
It came with Panther installed, but also came with Tiger on a DVD.
I did an 'erase and install' of Tiger, and it runs incredibly well.
At first, I was worried about only having 256mb of ram, but so far I've been really impressed.
Tiger runs really smooth on my 14" iBook (1.33 ghz). I think you'll be really happy with it. It's a little sluggish when Photoshop, iTunes, and Firefox are all going at once, but without Photoshop going it's pretty quick.
Honestly, I like how it works so well that I am considering upgrading to a gig of ram, and selling my desktop (3.2ghz p4).
Don't have any worries - even at the lowest ram possible Tiger runs great!