Google no longer offers a free version of Google Apps for businesses.
Instead of having a choice between a free and a premium version, businesses wishing to use Google Apps now have to pay $50 per user, per year.
This version gets them 24/7 phone support, a 25GB inbox, and a 99.9% uptime guarantee.
The reasoning behind the change, explained in an official blog post, is that businesses "quickly outgrow" the basic version. While this may be true, we can easily imagine many micro-sized businesses who are doing just fine with the free version.
On the upside, things won't change for existing customers, i.e. they'll still be able to continue using the free version.
Furthermore, Google Apps is still free for individuals, and Google Apps for Education will continue to be free for schools and universities.