As the owner of a Linux Gaming website www.gamingonlinux.com I often pulled Phoronix up on their over hyping of this story, that is until i shot Gabe (owner of Valve) an email to his personal email myself to ask if 1 - its coming to linux and 2 - if it would be out before the end of the year.
To my shock Gabe actually replied and said yes to both.
Phoronix also showed a photo of Left for Dead 2 running natively on Linux so that looks to be at least one Source Engine game coming to Linux, no doubt the new Counter Strike: GO will support us too.
The thing with Desura is while it's a good idea the Desura client is honestly rubbish as it is now, very buggy and no official support other than the Desurium open source client which is development is rather slow on (i think part due to lack of official support from Desura). One of the best things about Steam is the community features around it which make it so big - Desura has none of this.
As for Gameolith while again i support them they have switched from Linux only to multi platform, have no client to keep up to date and are slow to update games - not to mention a tiny library.
I am keeping my eye on but even with Gabe emailing me, i still remain skeptical :/