[wseymour]

"I was looking for a framework that supported PHP 5.3"

You didn't look hard enough - see Lithium

http://lithify.me

[elliotanderson]

Or Symfony2/Silex (based on Symfony, but designed more like Sinatra)

http://symfony.com/

http://silex.sensiolabs.org/

[conradfr]

and soon Zend Framework 2.

[Pawka]

...which even does not have RC yet...