In the form of an in-game notice Blizzard states:
We're aware of an issue that is causing player profile data to disappear. This can include friends lists, avatars, ranking, or profile information. A fix is currently in development to be implemented with the database reset scheduled for this week. Until that time, logging out and back in may temporarily resolve the issue. We apologize for the inconvenience and hope to address it as quickly as possible.
Hopefully we will also see the release of the Galaxy Editor, or perhaps the Mac version of Starcraft 2 Beta, that Blizzard previously announced would be released in April; alongside the server refresh.
