Wine 1.2 RC5, like the previous release candidates, just contains translation updates and bug-fixes. Officially there are 50 bugs that have been squashed over the past week for Wine 1.2 RC5.
The release announcement for Wine 1.2 Release Candidate 5 can be found at WineHQ.org. With the Wine crew liking to release on Fridays, it doesn't look like the official release of Wine 1.2.0 will make it out in June as was planned but more than likely will be a July release. Wine 1.0, the last major stable release of this free software project, was released in June of 2008.