[Kip Russell]

There is no law I am aware of which disallows guns in the workplace

This article:

http://www.bloomberg.com/news/2012-12-12/guns-to-work-laws-spread-in-u-s-as-business-fights-group.html

indicates that there are a number of states that prohibit employers from disallowing employees from having firearms in their vehicles on company property; PA does not appear to be one of those states, though there was legislation pending as of the date of the article to rectify this.

That's not the same as a law which prohibits firearms at workplaces, but the Brady Campaign appears to give PA 2 points for not protecting the rights of employees to store firearms in their vehicles while at work.

or on college campuses.

This appears to have changed quite recently:

http://www.insidehighered.com/news/2013/05/13/pennsylvania-universities-limbo-over-guns

http://pittsburgh.cbslocal.com/2013/05/13/some-pa-state-schools-now-allowing-guns-on-campus/

[Red in Blue PA]

In PA, if a mall has a no guns sign posted, and you carry concealed into the mall, you will be fine unless caught of course. And if you are caught you will be asked to leave. If you are caught coming back doing the same thing, you will be cited for trespassing. That is the law. I believe it is similar for workplaces and colleges. No serious charges can be brought AFAIK.