Yesterday, we announced a Magic Online Wide Beta Spotlight starting on Wednesday, May 7, 2014, after Magic Online returns from downtime and continuing until 10:00 AM PDT on Friday. During that time we'll also launch Journey into Nyx Prereleases on Magic Online; those will go live on Thursday, May 8, at 10:00 AM PDT.
You should read the whole article by Chris Kiritz about the spotlight and about what we've done to improve stability in the Beta client:
As I've mentioned before, we brought an external team of platform specialists onboard to address some of the foundational issues with the Wide Beta that were contributing to its stability and performance issues. We set a stability and performance bar for the external team to reach before moving back to feature development, and we're happy to announce that with the build released on April 9, we reached that bar.
Go read the full article for more information!