Inevitably, as soon as I'd posted, I found the answer.
Apparently, the MMC is the way forward:
1. Start > Run > MMC [Enter]
2. File > Add/Remove Snap-in...
3. Add
4. Select "Shared Folders" > Add
5. Finish
6. Close
7. OK
8. Expand the +, and select Sessions.
If there's someone connected, then it'll show up there.
What I wouldn't give for smbstatus!