I still highly recommend the Thinkpad T-series line, now owned by Lenovo, for running Linux on a laptop. I've been running Linux on various generations of the T-series since when IBM introduced the line (T21 running Fedora Core 1-4, then Gentoo), and I've never had any significant or insurmountable problems. They use mostly Intel parts and Intel tends to be fairly open source friendly which leads to them being easy to support. My current laptop is a T430s running Gentoo, and my prior laptop was a T400 also running Gentoo. Sleep/hibernate both work as does all the other features (video camera, ultrabay, etc.). The build quality is quite solid too (I only replaced my T400 because I wanted more than 8GB of RAM).
I have less experience with the other Thinkpad lines, but I would imagine both the X-series & W-series would also work well. If you go with a different brand, I generally recommend going straight to the business line (i.e. Dell Latitues, etc.) of the laptops for better build quality.