Hmm, I found some information that may answer my own question...
PVU licensing
IBM Notes and Domino
http://www-01.ibm.com/software/lotus/notesanddomino/domino-pvu-licensing.html
"If you wish to host collaborative applications for access both outside and inside your company, but do not need mail and calendar, processor value unit licensing may be the most cost effective for you.
You acquire server licenses determined by the total processor value units associated with your server machine(s).
Client access licenses are not needed for Web browser access to non-mail IBM® Domino® applications. Access from a IBM Notes client is allowed, but a IBM Domino Enterprise Client access license must be acquired separately for access to applications using the IBM Notes client software, regardless of whether the access is authenticated or anonymous. Two IBM Domino server options are licensed in this manner: "