Where is the development version of TRAMP?
If it's in the Emacs repo, as I suspect, then it won't be going into MELPA, for the same reasons that python.el was removed from MELPA: primarily, that code from Emacs trunk is frequently incompatible with older Emacs versions because it is ruthlessly updated and stripped of backwards-compatibility code.
Makes sense in general. Not sure about this specific case.
In general we take that view that if users really want to use the latest versions of libraries included in Emacs HEAD, then they will run Emacs HEAD. That's what I do myself, for ruby-mode and others.
Presumably, a month from now this will be moot anyway, because I expect that the faster TRAMP will be in Emacs 24.4.
That would certainly be nice