Err, yes actually. I only listed the WAN/router style interfaces, not all 3000 or so device drivers in the kernel!

So, yes, Linux has full ATM support, which means it also works fine with many popular USB ADSL routers, including: Speedtouch, Conexant AccessRunner, ADI 930 & Eagle, and others which share the same chipsets as those listed.

EDIT: Note that some of these (eg. AccessRunner) require downloadable firmware -- rightly not part of the Linux kernel -- and this all works fine with the in-tree kernel drivers.

Cheers