Mapserver License?

[Map Man]

Hi Folks,

Just researching open source options and probably covering an old topic,
but I'm looking for clarification on the current Mapserver license.

I was under the impression that it used to be part of the GPL or Gnu
Public License, but now I see that, according to
http://mapserver.gis.umn.edu/License, it is essentially freeware.

So I'm wondering if an interface to Mapserver needs to be open source as
well, and if one may charge for an interface that uses portions of
Mapserver.  Or must any fees be only for service and support of the
interface?

Also, is it possible or likely that the license may change in the future?

Thanks, and happy mapping!