That and they found enough things that needed fixing, I think. From the patch notes:
We are turning off the Foundry for the rest of the week and it will remain off until we can address several related infrastructure issues.
The Foundry will remain off while we release the Season 3 update to Holodeck on Thursday. The Foundry Open Beta will then resume on Tribble sometime later this week and possibly next week and will remain on Tribble until we are confident it can be supported on Holodeck.
So, we might see it back on thursday, but it might even be next week.
I did not realize they posted the Developer post in the live server area of the forum. I went and read it early this morning.
On a high note, the developers were smart to post they were shutting it down for two or three days. They know the players will go 'ah shucks' and wait a day or two to play the game. I was in the middle of writing a cool scene with the dialog on my first story I wrote. I made some changes based on some feedback. I made some new sets for the story.