I just got a new Thinkpad X220. It is a nice piece of hardware. I installed ubuntu 11.04 and am playing around with various setting to optimize its performance.
First, install gpointing-device-settings. This will allow you to tame the touchpad. Second, install laptop-mode-tools. This enables all sorts of battery saving tricks when you are on battery power. With the stock 6 cell battery, I am getting battery life estimate of 8-10 hours, although I have not verified this by leaving the laptop running. Although I should also say that most of the time, I am programming, which may actually be a fairly low power operation. I do have wifi enabled and firefox open as well.
So far I really like it. The keyboard is great. The layout is vi friendly and most of the buttons feel like they are where they should be.
I am getting used to the touchpad, it does feel like I am getting better with it, (and using gpointing-device-settings definitely helps). However I would not say the touchpad is great. Due to the thinkpads having the trackpoint, the physical buttons are above the touchpad, which is not what I was used.
The X220 seems to work fairly well out of the box with Ubuntu 11.04, I did not have any showstopping driver issues. That said there are currently a few shortcomings with the linux support for the HD 3000 graphics, those may not be resolved until 11.10, so that kind of sucks, but accelerated 3D is not a big reason for me getting this laptop. Compiz runs fine, so that's really all I need.
Anyway, I am very happy with this little laptop. The design is simple, but most things seem to be just right.