This seems like a duplicate. What failures are you seeing?
It would install from the .deb just fine, but running steam would complain about missing files and then segfault.
Having figured out how to get it installed, I can no longer reproduce the actuall errors.
To see for yourself:
This should be fixed with the latest steam package (1.0.0.50) available from steampowered.com
Nothing extracted yet.
In order to successfully install Steam from Ubuntu Software Center of from a directly downloaded .deb, the Catalyst drivers must be uninstalled, the Open Source drivers installed, Steam installed (it will install to completion) then Catalyst re-installed.
Once initial installation is complete the client works fine.