PTLens?

[David Oswald]

Ok, I give.  I keep hearing about the PTLens plugin for PS.  And an hour 
or so ago today someone on the list here even mentioend the fact that I 
could use PTLens to correct my 17-28mm fisheye's images such that they 
render as a  rectilinear image... particularly interesting to me as an 
*ist-DS user looking for a wide angle option.

But having googled quite a bit I still can't figure out where/how/etc.
Where do I find this plugin?  How do I install it?  Or at least, where 
may I read and research my own answers to those two questions?

Thanks in advance for suggestions...
Dave