Having issues with Xcode 4.1 upgrade on Lion?

So you've upgraded to Lion and you want to upgrade xcode to 4.1 as well.
Should be simple, but surprisingly while you install the upgrade of xcode you are stuck on iTunes not closing properly.
Well in fact you can close it but xcode installer seems to miss this fact.
You ask yourself what's going on?

Does it sound familiar?

The reason is simple. Even though you close iTunes (BTW: why can't xcode installer do it by itself?) there is still iTunesHelper in background blocking Xcode installer.
So all you have to do is to open Terminal and issue:
$ ps -ef | grep iTunes
  501   406    96   0 12:49AM ??         0:00.14 /Applications/iTunes.app/Contents/MacOS/iTunesHelper.app/Contents/MacOS/iTunesHelper -psn_0_180268

$ kill 406

where 406 is pid of iTunesHelper

or simpler:

$ killall  iTunesHelper

Have fun :)

PS: That's something new for Apple to have QA issues.