You may have noticed a week or so ago that the Zune software asked to be restarted in order to access "new features." The only change was the removal of the Windows Phone Marketplace from the Zune software. The reason given by Microsoft
was basically "not enough people used it," and they wanted to focus their efforts on the phone and web versions of the Marketplace. They also announced that support for pre-Mango devices would be cut from the Marketplace, though that changes should affect very, very few people. But what if you still want to use the Zune software to find apps for your Windows Phone?
There's actually a few ways to do this. First off, any app over 20 MB will require either Wi-Fi or use of the Zune desktop software in order to avoid eating up large amounts of your data plan. This doesn't let you browse though, and for that you'll need a few more advanced solutions. The first is to use your computer as a server (I believe some old Zune hacks as well as the Zune screenshot OpenZDK app used this) in order to serve the Zune software a specific file. The change that disabled the Marketplace in the Zune software was a single line in an .xml configuration file. Switching this back and redirecting the request for this file to your own machine would serve back the old file to the software, re-enabling this function. This does require the knowledge and ability to actually set up this server and modify your hosts file to redirect the request, which is a less than ideal solution. A reader of WPCentral named Thomas W., however, managed to find a method that does not require such setup and accomplishes this with a single registry edit. Now, to preface this advice, editing your registry can be dangerous if you don't know what you're doing, so before attempting this you should back up your registry (it's a function inside of the editor via File>Export) and ensure you are placing the right key in the right place before saving your configuration, and touch nothing else while doing this, and ensure that the Zune software is not running while doing this. If you follow the instructions closely, no harm should result. The steps are pretty simple. First, open regedit.exe with administrative privileges, then navigate to HKEY_CURRENT_USER\Software\Microsoft\Zune. Right click the Zune entry on the left and select New>Key, and call it FeaturesOverride. Then while inside that key, right click the empty space on the right pane and select New>DWORD (32-bit) Value. Name it Apps, then right click it and select Modify. Change Value data to 1, then click OK. You can then close regedit.
Again, please don't attempt this if you aren't comfortable with advanced system tools like regedit. The actual chances of something going wrong are quite low if you follow the instructions carefully, but delving into the registry is not for the faint of heart. This will work for the time being, but should Microsoft choose to update the client in the future that ability to do this may be removed. In the meantime though, enjoy!