Qt 5.0 has had a hard time making it out the door with the major tool-kit update originally was supposed to be released this summer, then was delayed multiple times, and in the middle of development the Qt Australia office was closed by Nokia followed by selling off the Qt assets to Digia.
This morning on the development list, Knoll Lars wrote that the RC1 had "a few issues that really should get fixed" so an RC2 release is necessary. However, at this time the Qt developers don't think a Qt 5.0 RC3 will be mandated. The aim is for this second release candidate to ship on Wednesday evening.
If Qt 5.0 RC2 pans out to not turn up any new bugs, Qt 5.0 will be presumably released next week.