[dagar]

A fairer comparison might be the X220 with the 6 cell battery which is about 2.9 lbs and around 10 hours (advertised). It also has a 12.5" IPS screen.

I believe the 3.6 lbs you mentioned is with the 9 cell 15 hour battery.

For comparison the 11" and 13" Macbook Airs are rated 5 and 7 hours, respectively.

[Steko]

It's 3.3 pounds with the 6 cell battery.

[jbellis]

2.9: http://shop.lenovo.com/SEUILibrary/controller/e/web/LenovoPo...

[Steko]

He links a picture that says 2.9+ lbs., which I'll guess is possible but reeks of dodginess given that 90% of the major reviews (cnet, pcmag, engadget, laptopmag, all quote 3.3 (or 3.5) pounds for 6 cell configuration, these are easy to find with google, here's one that weighed it himself:

http://www.studenttechguide.com/2011/08/lenovo-thinkpad-x220...

I'm guessing 2.9 pounds might be for the originally planned 3 cell battery version which may be offered somehow but is not configurable through the online order at lenovo.