The folks over xda are doing a great job with all the new Windows Phone 7 hacks, but it seems that the HTC devices are the ones getting all the fun there.
For instance, the member xboxmod have found a way to install provxml on WP7, and hence total access to the registry, which allowed them to change the WP7 themes with custom colors, disable relocking the phone once unlocked with ChevronWP7 and a lot of other stuff.
On the other hand, a lot of the member have been asking if there is a way to do so on Samsung devices (Omnia 7 and the Focus). While we have access for read/write on the registry for Samsung devices, it is so limited compares to the provxml method on HTC devices.
I developed a simple app showing how to write the registry using the Samsung native DLLs, so hopefully some guys will pick this up till we come up with a full functioning method to manage the registry on Samsung Devices.
This is the link to the application (the XAP file with the source code), you find in the same thread a homebrew registry viewer too which allows the traversal of registry keys.