I have just updated my Ubuntu Wubi installation on my Thinkpad X200 to the current state of the development release equal to 11.04 Alpha 3.
Given the fact that this is an alpha state software it really works well, I get random application crashes but nothing that would ruin your day.
There is one annoying bug however, the LCD brightness per default is at almost 0. To increase brightness until this is fixed type the following command into a terminal:
sudo bash -c "echo 4 > /proc/acpi/ibm/cmos"
Warning: it is strongly advised not to install pre-release software on a production system!