It is now possible to side load apps and games (.xap files) on to Windows Phone 8 devices that have microSD card support (Nokia Lumia 820, HTC 8S, Samsung ATIV S). The .xap files still need to come from the Windows Phone Store, and a a data connection and an active Microsoft account are still required to successfully install apps.

The .xap files are first downloaded from the Windows Phone Store (using a manual download link), then copied to a microSD card. On opening the Store app on the phone a SD Card option becomes available, from where the relevant apps can be installed. Free apps can be used immediately, as can trial apps, but paid apps must first be purchased before they can be used.

When listed on the phone the Store app will automatically detect any apps that are already installed. This side load method will only install apps that are available in the Windows Phone Store and will only work if the version of the .xap file on the microSD card is the same at that in the Windows Phone Store (i.e. the latest).

The feature is useful for those with limited connectivity on their device (some games and games are more than 50MB in size), or if you are are setting up multiple devices. It might also be handy for those who want to keep a specific list of apps on hand, but don't necessarily want to keep them installed all the time.

The manual download link for any app or game can be found at the bottom of the left hand column on the listing page for the app on the Windows Phone website (look for "Download and install manually").

Via: WMPoweruser