I booted up a Fedora 15 Beta RC2 Live CD on a new ThinkPad X220 and it seems to work fine. I am posting from this X220 on WLAN running Fedora 15 Beta RC2.
Note that an F14 Live CD would not boot up to a desktop. I am glad to see F15 working.
I'll wait for F15 final before installing it though (dual boot).
Got a bug report on my Sierra Wireless 890 AirCard as it will not connect to the internet. To even configure the card, you have to launch an app from the command line.
No minimize / maximize buttons in Firefox (probably other apps as well). Have to download and run gnome-tweak-tool to get those buttons back.
Cannot disable my Touchpad in Gnome.
Mandriva 2011.0 KDE Beta 2 is looking more promising atm (yes, booted from my X220). None of the 'bugs' or 'features' above. My complaints about Mandriva are poor looking fonts, and searching for software not working properly yet (probably will be fixed before release). Mandriva is also slow to boot up - at least from the Live DVD (others say from the hard drive as well). No Intel WiFi drivers on the Live DVD - have to get them from a different type of internet connection. Mandriva is much more configurable than Fedora.