While you still need to be developer unlocked (sorry Sprint Arrive users), this is a pretty big step forward in the homebrew arena for Windows Phone 7. It allows you to sideload XAP files and it even has its own protocol handler (wphome:), similar to zune:. There’s been a few Windows-based XAP installers out there for a few months now, but this one seems to do a little more than those.

The features outlined so far include:

• In-place update on the phone: In-place update on the phone, e.g. if you already have Version 1.0.0.0 of an app installed on the phone and install 1.0.2.0 an in-place update will performed. No more full “uninstall-new install” cycle required. Your settings, custom files etc. won’t be removed (same as marketplace update)
• Deploy from file or URL: You can either specify a file or an URL. If you enter an URL the installer will automatically download the xap.
• Own protocol “wphome”: Zune’s one-click download for homebrew apps. Automatically install homebrew XAPs with a click on a hyperlink. If you want, you can register the application for the wphome protocol. The application will then be allowed to handle urls like wphome:www.test.com/test.xap and will automatically start as soon as you click on such a link

Source: XDA via WPCentral