The fix (particularly for dynamically assigned IP addresses) requires that we:
1) resolve the IP address for every hostname that you want to exclude
2) cache it, and periodically update it (e.g., every 24 hrs)
3) iterate through the list for a match
I am interested in that same idea, and i try to get a plugin for that.
I pulled together all what was written about the topic so far [http://forum.piwik.org/read.php?3,84238]. among it, an existing (dirty) solution, but this needs a shell-script.
So it would be great if interested people come back to that thread, and tell us what exactly their needs are.
Please see this ticket: #3589 Admin: Global list of Excluded Host names