You may want to register for the openmoko GTA02. Should soon be available to developpers.

About the Zaurus linux palmtops: I think that their last model has been discontinued over a year ago.

OTOH, if you have big pockets, an ASUS EEEPC may be what you need. Or any one of the palmtop sized PCs which are available for sale in Japan (full PCs running windows, but I am sure some can run Linux as well). Disadvantage: the battery doesn't last very long.