Windows 8 "Release Preview" is out now. Originally planned for the first week of June, it looks like Microsoft couldn't wait that long, and so has shipped the software a day early.

The Release Preview is the third in Microsoft's trio of Windows 8 pre-releases. The first was the Developer Preview, back in September of last year. Instead of following up with a more traditional "beta" release, Redmond branded the next version, launched in late February, the "Consumer Preview." This final version would more traditionally be known as a Release Candidate.

The operating system is now almost complete. Compared to the Consumer Preview, the new version will include integrated Adobe Flash, greater customization of the Start screen, improved multimonitor usability, and a broadly improved fit and finish. What it won't include is the new theme that has been announced, so visual inconsistency between the desktop parts and the Metro parts will remain an issue.

The biggest changes in the Release Preview will perhaps not be in the core operating system at all. Rather, they will be found in the application ecosystem. Microsoft's own bundled applications—the ones replacing the Windows Live suite—and the Windows Store application itself have both been updated, and in the Release Preview, unlike the Consumer Preview, we can expect to see a much wider range of applications, both first- and third-party.

How many apps there will be is still unclear. Dina Bass at Bloomberg has written about Microsoft's efforts to court developers and populate the Windows Store with a range of touch-friendly Metro-style applications. While some developers, such as Corel, have leapt at the opportunity, others, such as Flipboard, appear to have no interest in the platform. Even Facebook has no plans to produce a Windows 8 application, according to Bass' report.

The next stop after Release Preview will be Release to Manufacturing (RTM), and after that, the retail release. Using the scheduling of Windows 7 as a benchmark, we'd expect the RTM sign-off to occur around August and retail availability around October. But it could be sooner still; we've heard claims that the RTM build is planned for only a month away.