In the PowerBook line, the keyboard was the same in the 15" and 17" models. Similarly in the MacBook Pro line.
There's some pictures of the 15" MacBook Pro versus a 15" PowerBook G4, and some commentary on the 15" and 17" boxes on [link|http://flickr.com/photos/rbassman/135646537/|Flickr].
Cheers,
Scott.
(Who isn't aware of a Thinkpad with a "full-size" keyboard, but there are boxes like the [link|http://www.gateway.com/products/GConfig/proddetails.asp?system_id=nx860xl&seg=hm|Gateway NX860XL] that come close. But, personally, I wouldn't want to drag around a 16" x 11" x 1.25+" box with me.)