I think his scenario is something along the lines of:

• Interesting post occurs 5 layers down in a thread (c.f. the recent threading discussion in meditations)
• He'd like to msg someone a pointer directly to that post, but to do so he's got to:
  • Copy the link from the node's title
  • Paste it into the msg box
  • Clean it up manually down to the [id://] format

If the nodes had a copy of the id number (perhaps next to the node's tile in a div that's hidden by default in the stock CSS) he could cut and paste from that easily, just like you can cut and paste from the Node Status Nodelet for the node you're actually looking at.