The Dish 5000 modulator is an add on to the Dish 5000 receiver. It will take the High Definition programing available on Dish (HBO, SHO, DEMO, PPV) and output it as an 8VSB modulated signal on either channel 2 or channel 3 of the ATSC OTA spectrum. What is so great about that? Well, it is one of the very few way to actually record satellite HDTV. You can feed the Modulator's output into a HiPix, Wintv-HD, or AccessDTV and record HD HBO, SHO, etc.
It was discontinued either 1) because the 6000 model was introduced which is much easier to use, or 2) because MPAA wants to stop any ability to record HDTV satellite and pressured Dish to stop making the device. You decide.