My MacBook Pro had it’s logic board replaced and I dreaded what the resulting new MAC address would do to some of the installed software.  Time Machine is one of the applications that cares.  The machine’s MAC address is used, in part, to identify itself with Time Capsule.  I was so concerned that I made a Genius Bar appointment to pickup my repair and talk about this issue with a tech.  The tech printed out a tech note entitled “10.5: Repair Time Machine after logic board charges”.

But after I got home I was pleasantly surprised to discover Snow Leopard knows about this problem and has a solution.  My first backup with the new logic board resulted in the following dialog:  “Would you like to reuse the backup “/Volumes/Data/Nemo.sparsebundle” with this computer?  The backup was created on a different computer.  If you reuse this backup it can no longer be used by the original computer.”  The options were “Do Not Backup Now”, “Create New Backup”, and “Reuse Backup”.  Clicking on “Reuse Backup” does all the MAC address fix-up while clicking “Create New Backup” will result in a new Time Machine database being created.