I haven't specifically installed Solaris on the two Thinkpads that I've owned, but I can vouch for them being solid laptops. They rarely overheat and have survived a couple 2-3 foot freefalls. ;)
Also, I did a quick google search and found that it isn't to hard to get Solaris installed on a Thinkpad.
I've used it on my Thinkpad X31, and everything works fine, except the trackpoint scrolling, which I can't get to work even with manual xorg.conf hacking. You can try the hardware compatibility list to get you started.
The same page also links to a tool which can check if you're current system is compatible with Solaris or OpenSolaris.
...and of course, if you're rolling around in more money than you know what to do with:
http://www.tadpolecomputer.com/
Very nice machines, had one for awhile. Extremely expensive though.
Acer Ferrari - at least that's the equipement people from Sun frequently use when doing Solaris or Java presentations and demos.
Thus my guess is this device has to be well supported by Solaris.
:-)