As we reported earlier 100k beta invites were sent out to North America two weeks ago and with Battle.net Balance all set up and done for North America last week, it seems that Blizzard is taking the stresstests to a new level. Starting this week they will put a lot of stress on the RMAH to see if it holds up under the pressure.
We’ll be placing extra strain on the beta auction house every day this week from 10:00 a.m. PST until approximately 12:00 p.m. PST, to put the system through its paces. During this time there may be interruptions or loss in an ability to use the auction house. We’ll provide updates if there’s any extended downtime experienced or expected.
I would suggest that you don’t use the RMAH during the stresstest just in case something goes wrong and you lose some of your Bobby Bucks and or items.
Source: Battle.net forum