What I gathered from a Dev post on the SWG board was that the station was set to go down for just one weekend to upgrade things in the background and maybe revamp their core members area. This meant that all the sites had to be knocked off and taken down whilst some of their free game servers were also upgraded etc. The sites such as Planetside and SWG weren't necessarily going to get a (complete) overhaul.
When they did this they linked that automatic "we're upgrading" page wherever they could so that everyone knew about it. For a couple of days after the station went back up they had a couple of problems where that page was shown where it shouldn't have been. After those few days the upgrade/update was over/done/finished (neglecting a few other problems meaning we still saw that page).
The devs must have planned to put something at .../beta a while ago and left it as an empty folder, we're just seeing the automatic "we're updating" page because there's nothing there. Lets just hope they put something there eventually.
Then again, I could be miserably wrong