> It was written under an NSF grant, so it's probably public domain?
Unfortunately, you can't assume that in general. There are a few specific NSF programs that require open-source licensing of any software produced (e.g. http://nsf.gov/funding/pgm_summ.jsp?pims_id=5174), but it's not a usual requirement. In fact lots of NSF-funded stuff eventually ends up in spinoff companies selling proprietary software, and the NSF even dedicates a smallish portion of its budget specifically to funding those kinds of spinoff efforts (via http://www.nsf.gov/eng/iip/sbir/).
Unfortunately, you can't assume that in general. There are a few specific NSF programs that require open-source licensing of any software produced (e.g. http://nsf.gov/funding/pgm_summ.jsp?pims_id=5174), but it's not a usual requirement. In fact lots of NSF-funded stuff eventually ends up in spinoff companies selling proprietary software, and the NSF even dedicates a smallish portion of its budget specifically to funding those kinds of spinoff efforts (via http://www.nsf.gov/eng/iip/sbir/).