Yeah, I saw the High tec Redneck site, but I didn't know how credible they were not being an official State of Pennsylvania website.
Best off to look up the statutes mentioned in erict's post and determine for yourself before you use night vision.
That having been said, I agree it looks like a no go.
EDIT: Here it specifically states infrared beam:
(ii) Exception as otherwise provided under subparagraph (iii), no archery sight or firearm's scope shall contain or use any device, no matter how powered, to project or transmit any light beam, infrared beam, ultraviolet light beam, radio beam, thermal beam, ultrasonic beam, particle beam or other beam outside the sight or scope onto the target.
Page 61:
PA Game Commission Title 34 Chapter 23 - Portal.state.pa.us