As previously mentioned, Joomla 1.6 reaches end-of-life today. That means there will be no security patches or other changes to the 1.6.x branch of the code.
The good news is that upgrading to Joomla 1.7 is pretty straight-forward.
I recommend taking a look at the docs.joomla.org article about upgrading to Joomla 1.7. There are several methods available. The easies way is of course to upgrade using the built-in updater. For some, however, this is not an option because they're on a shared host or similar. Some hosts do not allow the methods that are required on the server for the upgrader to work. Therefore, you might need to upgrade your sites manually even if there is a built-in upgrader.
Take a look at the . You can also read my article about Joomla 1.7 status and upgrade info.
Joomla 1.7 is here to stay, for a while at least, so you should upgrade as soon as possible.