The free version of Google Apps (that we've been such a big fan of!) has been discontinued as of Dec 6, 2012.
If you were already a Google Apps customer at this time and used their free version, you will not have to start paying for the service unless you need to add an 11th (or more) user.
If you're already on the paid version of Google Apps, then nothing is changing for you either, but you no longer have the option to downgrade to the free version.
If you have not signed up for Google Apps, but were planning to, you won't have the option for the free version. Don't worry though - it's still a very affordable option. You can learn more about google.com.
Here's the official information from Google about the update, if you're interested in reading more: http://support.google.com/a/bin/answer.py?hl=en-us&answer=2855120