Usability 
Since 1994, print magazine Linux Journal has been covering the open source OS from all angles with news, editorials, reviews, and how to articles on using the Linux and developing software for it. The articles cover a wide range of skills levels from beginner to guru kernel hacker. The quality of writing is very high for a tech magazine, hardly surprising as well known blogger and co-author of the Cluetrain Manifesto, Doc Searls is senior editor and writes many of the opinion pieces.
Linux Journal has an online edition, launched in 1997, which includes selected current content from the magazine and a searchable archive of back issues. Only paid subscribers can view the full content of the last two issues online but anyone is free to read older issues. Visitors to the site can add comments to any article. The Linux Journal online also features a user forum and links to third party Linux resources.
I recently ran across the mobile edition of Linux Journal (m.linuxjournal.com) and it's a beauty. No tiny dumbed down mobile site, it features just about everything found on the full site including archives, commenting, forums and videos in mobile format. The only thing I found missing in the mobile edition was a site search. The well designed site is easy to navigate with a mobile browser but you will need a fairly powerful device as page size can be large. The articles are not paginated and contain all the full sized images from the PC version. Pages can be several hundred KB, well above the 20 KB maximum page size that the embedded browsers of many dumb phones can handle. Sounds like a job for a device running one of the mobile Linux distributions! While you are waiting for Android or Verizon's LiMo phone you should be able to use any modern smartphone or any phone running Opera Mini to read the mobile Linux Journal.