I can access it and post without any problems. Some sites, however, have a special theme for mobile browsers that removes the graphics and the column widths (i.e., it lets the text wrap naturally). For example, check out these sites:
Search
http://www.avsforum.com/avs-vb/index.php?styleid=13
The Qusers site is probably too minimal - I'm not looking to filter out information, just formatting. AVS is a better example, and I believe they use vBulletin as well. It looks like they just use a theme.