As of 0630 GMT all instances have been migrated to version 2 and the back office systems have run through all feeds twice and passed a small number of MTurk transactions in both directions.
You are now free to login and resume normal operations. The system is backward compatible with version 1 so there is no *requirement* to change anything. I'll publish release notes during the day Sunday.
If you see anything missing or broken in your instance please email support immediately.