So to summarize, lots of reports of legitimate sites being trashed, and lots of talk about a rollback of this update.
The thing is, there has already been an official announcement of this update on the official Google blog.
Google is going to look pretty dumb if there is indeed a rollback, even if it's partial.
Also, the announcement specifically mentions that it is an "improvement" to the algo, not "we're testing an algo change" or anything of that sort.
Looks permanent to me.