TDM 2.07 is primarily a stability release, aimed at improving several experimental features that were added in 2.06. Soft shadows now work better, for example, with fewer graphical glitches and a new Shadow Map mode that allows for contact hardening (and generally better performance).
In addition to greater stability, there are a few new gameplay features, including a new frob helper that can be turned on in the Gameplay menu.
Mantling low and medium-sized obstacles is now faster and smoother, and further mantling improvements are already in the works for the next update.
There are a few new assets included in the update, including some new architectural module pieces, new chain models, and several trap prefabs (along with videos on how to set them up).
To update to this version, simply run tdm_update.exe in your darkmod folder.
edit: Nbohr has posted a lengthy, illustrated description of the changes here: https://www.moddb.co...ability-release