Thanks to Myth Village for this heads up as posted on their site:
Why so long, you ask? Well, Bungie's TFL map making tools were never officially released, and technically they still haven't been. I guess the better question is if we're even supposed to be able to download them now. All that aside, if you want to make TFL maps with the original tools made to do it, get them at The Mill. How functional they are is anyone's guess (but scripting capabilities have been rumored, and you TFL map makers know what a big deal that is). Update: these tools are Mac only