Tone mapping as done in Photomatix is part of one of the various workflows that allow one to convert a number of differently exposed shots of a scene to a single image with a wide dynamic range. I don't believe Lightroom provides any capacity for combining differently exposed shots of a single image and I doubt whether doing so would ever be part of its development path. Photomatix comes with an excellent LIghtroom plugin.
BTW, for windows users, Oloneo is a very promising beta of a new app for HDR imaging. Well worth a .look, IMHO, although it doesn't as yet integrate very comfortably with Lightroom.
My relationship with Photomatix has been troubled, but I have always been willing to attribute that to my failings rather than those of the program. It is very powerful and can achieve a wide range of "looks" as well as the stereotypical HDR style but I have never really learned to drive its user interface. "It's me, it's not you" will be my parting words if I do end up duming it for the "cheese eating surrender monkey" charms of Oloneo, which is notably easy to - ahem - drive. Don't misunderstand me - some of my best friends are frenchies. Remembering that this is a Lightroom thread, I would end by saying that Lightroom integration will be a deal breaker for me. At this point, Oloneo won't even open tiffs exported from Lightroom. I have raised this with the developers but haven't had a reply.