I have gotten a bit tired of loading up parameter files by hand, so I've added a very simple command line to do this:
yt load [your_parameter_file]
will start up an IPython session with the parameter file you specify in the variable 'pf'. IPython has a lot of really great features: http://ipython.scipy.org/doc/stable/html/index.html , and we're going to see if we can get yt tab-completion and some other fun things implemented in the near future.
I didn't back port this feature to 1.6, but if you're on trunk, it's on the latest revision.