So, Puppet or Chef? A question of configuration automation & provisioning that has started more than one flame war in its time. Whilst perhaps not helpful for those charged with implementing an automation solution for their business the most appropriate answer really is "It depends." Many have argued that (considering the alternative) using either is fine. Just get started!
There are differences though, both with the technologies and the companies behind them, that an understanding of both may make your choice a little easier.
* check out Puppet vs. Chef Revisited for an updated comparison.