I just upgraded someone's laptop from an IBM/Lenovo T60 with the extended battery to an IBM/Lenovo T61. The W/D/H is 13.2"x9.3"X1.3". It has the wide aspect ratio screen I was worried that it may not fit in my Brain Cell, but it does! Without any trouble at all. It just dropped right in.
I'm ordering the T61P for myself. It's slightly larger at 14.1"x10"x1.4". I'm not sure it's going to fit, but I'll try it as soon as I get my hands it.