XDA-Developers users are well known for their abilities to cook custom ROM"s for a range of phones, from Windows Mobile in the early days to Android now, and it looks like a group of users by the name of the "Dark Forces Team" have done it again, this time for Windows Phone.
According to WPCentral, DFT has released the RSPL/HSPL tools for the platform, which enables "ROM Chefs" to build custom ROMs for their (and many others") Windows Phone devices. Currently, the tool only works with the HTC Mozart, HTC Surround, HTC Spark (Trophy) and the HTC 7 Pro, however it is not compatible with the Sprint Arrive or the Verizon Trophy.
HSPL stands for Hard Secondary Program Loader which is modified in the tools to disable the carrier ID check and the NBH signature that forces only official images to have the ability to flash onto devices.
It"ll be interesting to see if users are actually wanting to develop custom ROMs for Windows Phone, or whether the tools are pointless. In the current releases of Windows Phone, "bloatware" that has plagued Windows Mobile and Android is not present, or can be uninstalled by the user.