Ubuntu 11.04 release schedule has been changed and now there will be no more a release candidate on April 21. Instead of that a new beta 2 will be released on April 14.
The changes were announced by Kate Stewart from Ubuntu release team. Excerpts from the announcement mail:
"After reviewing the plans at the end of this release, it was felt that a release candidate release on April 21st showing up just before the easter holiday would be a bit late. After discussing this with the key stakeholders and not getting any negative feedback from them or in the weekly release meetings, we're going to go ahead and add a Beta 2 for this release, and drop the Release Candidate from the Natty Schedule."
Alpha 3 - March 3
Beta 1 - March 31
Beta 2 - April 14
Final Release - April 28