Hi there,
We wanted the same info from all of our Notes users awhile back...instead of a logon script, we used an email to all employees that contained a button to click. The button code generated an email specifying the notes client version, and returned an email to the admin. I found this on another forum (sorry...), as I no longer had a copy of the original message we sent. Hope this helps...
Here's some code you can put into a button:
dim s as New NotesSession
dim doc as NotesDocument
dim body as NotesRichTextItem
set doc = new NotesDocuemnt(s.CurrentDatabase)
doc.Form = "Memo"
doc.Subject = "My Notes version"
set body = new NotesRichTextItem(doc, "Body"

call body.AppendText("My notes version is " & s.NotesVersion)
doc.SendTo = "desired email address"
call msg.Send(false)
Good Luck! This worked like a charm for us!