It seems Microsoft has backtracked on a policy that said it would reject any app with 'Metro' in the title. In other words, it would not make it past the approval process and, as a result, would not appear in the Windows Store for any and all to download. The folks at MarkedUp were first to spot this note in the 'Naming your App' section of the Windows 8 app developer guidelines.
"Note: Make sure your app name doesn't include the word metro. Apps with a name that includes the word metro will fail certification and won’t be listed in the Windows Store," the guidelines advise.
However, it seems Microsoft has backtracked, as Ars Technica reports that this was quickly replaced with a simple reminder not to infringe upon any existing trademarks.
"Make sure to select a name for your app that belongs to you. If you use a name that doesn't belong to you, the owner of that name could have your app removed from the store," Microsoft warns. "If that happens, you would need to change the name of your app and all instances of the name throughout your app and its content before you can submit your app for certification again."
Microsoft is currently working to eliminate the Metro brand and replace it with a new name. Microsoft says that its decision was based on the fact that the Metro UI brand was just a codename that it had long planned to change closer to the Windows 8 launch. However, there's also reports that the company was facing pressure from a European company named Metro AG.