Computerworld writes that Metro apps for Windows 8 will only be available via the Windows Store (Microsoft’s version of the App Store), and like Apple, Microsoft will take a 30% cut. From the article:

[…]Microsoft confirmed that the Windows Store — the official name for what executives have referred to as “our Windows app store” — will be the sole distribution channel for Metro apps, those that run in the Metro interface in Windows 8 on Intel-powered devices, and the only ones that will be permitted on ARM-based Windows 8 tablets.

Regarding the app vetting process, which in the past has landed Apple in hot water:

Dworkin also told developers that Microsoft will vet each submission and ensure that Metro apps are malware-free. “We will examine every application that will be submitted to us [and] we will run a virus check and a malware check on every application,” Dworkin said.

This quote paints the process as only checking for malware, unlike Apple who also rejects app submissions based on content such as pornography.