Even though Microsoft is very close to completing the RTM version of Windows 8, the Release Preview version is still out there and being used by a number of early adopters. They have also been downloading and using the Windows 8 Metro apps that are available for free on the Windows Store.
Today, McAkins Online
says that as of today, the Windows Store has 400 apps to download
for Release Preview users of Windows 8. While that number may seem small, keep in mind that this is for a pre-release version of Windows 8 and that there are likely a lot more Metro apps to come before Windows 8 hits retail.