I tried the iskin and the marware screen protector (a piece of neoprene you lay on the kb when it's closed) but when I closed my PB it felt too tight, like there was too much pressure on the latch.
I didn't like the iskin on my 12"pb because there was some overlap off of the keyboard, and it felt funny. It's too bad because tons of crap likes to fall onto my keyboard.
If you want to use the iskin and a screen protector I recommend the screensavrz from radtech because it's pretty thin.