Uh...there are a ton of "tone mapping" tools already in Lightroom's Develop module. Exactly what are you trying to do?

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.

Yes, so often an HDR picture produced by Photomatix (or other similar programme) looks as though it's made up of internally glowing elements - totally artificial to my eyes.