Dragon NaturallySpeaking is still alive at least in medical practice. Its Nuance Dragon Medical One product is fairly popular in some regions for medical report dictation as radiologists don't like to write them down (sorry ;) ). I've seen a Philips product in that field too. Seems like LG's TVs used their recognition engine for a while (don't know if that's still valid)

The story for the most mainstream-popular dictation softwares is kind of funny. Back in the late 90's there was Dragon NaturallySpeaking and IBM's ViaVoice. In early 00s, after a financial fraud and bankruptcy involving both the then current Dragon owners and Goldman Sachs, they got bought by Scansoft. Scansoft bought Nuance, began to use its name, and then got exclusive rights for ViaVoice (!) from IBM.

Now, in March this year, Nuance has been acquire by Microsoft.