Hi, I'm Ricky Kirkham from the developer documentation team for SharePoint 2013. I'd like to let you all know how you can use the app manifest to specify which locales are supported by your app for SharePoint. You are required to specify supported locales, or your app will not be accepted by the SharePoint Store.

The <Properties> element of the app manifest must always contain a child element that identifies the locales that the app supports. For the final release version of SharePoint 2013, the element is <SupportedLocales> and it must have a <SupportedLocale> child for every locale that the app supports, even if there is just one locale. (An app can support a maximum of 25 locales.) Note that you identify the locale with the CultureName attribute. The value of this attribute is a locale identifier in the Internet Engineering Task Force (IETF)-compliant format LL-CC. The following is an example.

<App … >

  …

  <Properties>

    …

    <SupportedLocales>

      <SupportedLocale CultureName="en-us" /> 
      <SupportedLocale CultureName="ja-jp" />
    </SupportedLocales>        

 
  </Properties>

  …

</App>

There are a couple of small, and temporary, extra points to know. First, for an undetermined period of time after the release of SharePoint 2013, the SharePoint Store will not have any UI to tell potential app purchasers which locales are supported by your app, meaning that all users will assume that all apps support the en-us locale. But, if you have localized your app for other locales, you should include them in your <SupportedLocales> element so that you will not have to upload a new version of the app when the store's UI is expanded, and so that users will automatically start seeing more locale options for your app when the UI supports this.

Second, if you have signed up for a SharePoint Online developer site, please note that it might not be converted to use the release version of SharePoint 2013 for a few weeks after release. While your developer site is still based on SharePoint 2013 Preview, you have to use the <SupportedLanguages> element instead of the <SupportedLocales> element. The SharePoint
Store will accept either element for now, but will switch in the future to allow only the SupportedLocale element.

The <SupportedLanguages> element has no child elements or attributes. Its value is a simple semi-colon delimited list of locales. The following is an example.

<App … >

  …

   <Properties>

    …

    <SupportedLanguages>en-us;ja-jp</SupportedLanguages>        

   </Properties>

  …

</App>

The <SupportedLanguages> element will continue to work even on the release version for some time, but it is deprecated in favor of <SupportedLocales>, so on new apps you should Always use <SupportedLocales>. And if you have a reason to update an app that uses <SupportedLanguages>, we recommend that you switch to <SupportedLocales> as part of the
update.

I hope this post helps your apps sail smoothly through the submission process!