Installer File Formats
The usage of "install" as the root tag has been deprecated in favour of "extension". This has been done to avoid conflicts with of tags in some formats as well as to better reflect the nature of the file format.
Joomla! 1.6 features a new trigger system for all extensions similar to the "installfile"/"uninstallfile" feature that components have in 1.0/1.5 releases.
Joomla! 1.6 deprecates the usage of "installfile" and "uninstallfile" tags in favour of the new "manifestfile" tag. Additional to this the "com_install" and "com_uninstall" methods are deprecated in favour of a installation class (e.g. ExtensionNameManifest).