MultiTouch is a new feature on recent models of the X60/X61/+ Tablet. It allows you to use any device that can create pressure (such as your finger) instead of the tablet pen. This feature is currently experimentally supported with linuxwacom. However, the tablet pen will still work on such systems.
with the wacom drivers, it will only support as a single-touch interface and not as real multitouch.
If you tablet pen does not work, try building the linuxwacom modules from source. You can find everything you need at their website.
[experience from x201 tablet] Today you only get 2 fingers from the display without pressure. The pen is working normal (with pressure).
A multitouch screen is an optional upgrade for the (non-tablet) T410s. As of January 2011, this is not recommended. Although it has some support as an input device, it seems to cause signficiant stability problems. On Ubuntu it prevents suspend from working; on both Debian and Ubuntu it seems to cause instability in X; and on Debian, while suspend works, wakeup from suspend seems quite unreliable.