I just wanted to say, that as far as package management goes, Valve probably doesn't truly need to integrate with any package management. They could probably just ship Steam for every distro and then it creates a folder(/usr/steam , /steam, /home/user/steam , who knows

) where it puts all Steam applications, possibly with a few libraries for easier compatibility. This may not be according to the current spirit of Linux, but I think it would make it easier for them to care for every distro and have compatibility. They'd just needto port Steam and it would be like their package manager, possibly even providing some necessary libraries that will differ greatly between distros(I mean like the same we use now, but the version they compiled the program with or they know it works better). Especially if they are to going to also have their own system to upgrade their software.