[update] Valve fixed the issues for Steam.app on Mac OSX. We will keep the file mirror for Steam active, since there will be faulty updates in the future for sure. Thanks for all the nice responses and donate us some TF2 hats, if you want to thank us ;)
Ok here is the solution for all you people that suffer from the current bug since the last Steam.app Update on Apple Mac OSX. Solution: Download an older version of Steam.app and replace Steam in your Applications folder of OSX until a new patch has been released from Valve.
SteamStartup(0xf,0x0xbfffec4c) failed with error 1: Failed create pipe:0
This is generally a good (temporary) solution for various Steam issues on Mac OSX, if you need to get your TF2 or Portal fix. Just use an older version of steam.app.
Download the old version of steam.app hosted by nanofunk.net to access your games! (currently all "source" games are affected such as TF2, Portal2, CS, Left4Dead)