This trivial note just because the wiki page about upgrading magento seems to be quite outdated ... or let's say it clearly ... wrong.

To upgrade magento from the command line (you would like to do it in case you have no public ftp access)

  chmod 766 mage
  ./mage mage-setup
  ./mage sync
  ./mage list-upgrades
  ./mage upgrade-all

this upgrades all the extensions and the core application.

This utility can also be used to install extensions:

./mage install community