Since Monticello is self-hosting, upgrading it can sometimes be a 
painful process.  To make this easier, I've posted a new version of 
MCInstaller (v10) on SqueakMap that includes an #unloadMonticello 
method.  Executing "MczInstaller unloadMonticello" will do the 
following:

- force you to save any MC packages with modifications
- cache all of the version info of currently loaded MC packages
- remove all of the Monticello classes from your image
- re-register the MCInstaller bootstrap loader as the handler for .mcz 
files

You can then load a new version of Monticello as if into a fresh image. 
  It will restore the info about loaded versions from MCInstaller's 
cache.

Hopefully this process won't often be necessary, but there have been a 
couple of transitions already where it would have come in handy, and 
I'm sure we'll run into a couple more in the future.