This will never change. What changes is the hash of the URL (e.g., #nabble-tt337174|a337174).
For example, compare these two URLs:
http://plone.org/support/forums/general#nabble-tt337174|a337174
http://plone.org/support/forums/general#nabble-f293352Basically, Nabble uses the hash to display the appropriate node.
Regards,
Hugo Teixeira
Nabble.com