Where can I find a trackplan of New York's Penn station - the current version?
Take two bottles, one with a narrow opening, another with a somewhat wider opening. Place them together bottom-to-botom. Point the narrower opening westward.
You now have a close approximation of Penn Station's present trackplan.
(Sorry. Couldn't help it.)
I'm not sure how easy it would be to find one on the Web anymore, but I believe the book, Passenger Terminals and Trains (Droege, 1916), had a Penn Station schematic. Out of print now, but I've seen it often on E-Bay. Check with the seller to verify that Penn Station is included.
Another book I dimly recall is Penn Station, Its Tunnels and Side Rodders, published in the late '70s. Also a possible E-Bay denizen.
I realize you want a modern schematic, but to the best of my knowledge (which will be promptly corrected if I'm wrong) there have been few changes to Penn's trackplan since it was built. The most notable being the LIRR West Side yards and the Empire Connection, both of which are more addendum than modification. Of course, dramatic changes from the original design have ocurred above the platforms, but that's a rant we all know too well.