Michael Kimsal has posted a few thoughts on one of the features of the upcoming PHP 5.3 - closures.

I first got acquainted with closures in Groovy last year, and love them. They make sense. The syntax is pretty easy, and feels natural in the language. Not so in PHP. Once again, inconsistencies are not just legacy issues in PHP - they are created anew for us to deal with for years to come.

He suggests that a different keyword (maybe, say "closure") to delineate between a normal function definitions and closures, especially when dealing with the Reflection API.