Does janusSEAL for Outlook Lite make end-users apply a classification to meeting (appointment) requests?

Yes.

With Outlook 2007 Professional and native Exchange 2007 message classifications, meeting organisers cannot apply a message classification to appointment requests. However janusSEAL for Outlook Lite addresses this shortcoming. When the organiser goes to send an appointment request the janusSEAL for Outlook Lite Classification Dialog is shown and the request is only sent once a message classification has been specified.