Excuse me, guys. I don't know where to post Steam related issues.
I am not inside Steam's Beta Participation, but using the regular edition. I started Steam and my 'Friends List' has automatically popped up as well. Then I switched to 'Community' tab to see, what has been up yet. Afterwards I changed from 'Community' tab to the 'Store' page and saw this:
http://h11.abload.de/img/steam_autoapp_def_001jpkz6.png