In this recent post to his blog Juozas Kaziukenas looks at one of the features in the next major upcoming release of PHP (5.3) - lambda functions (anonymous functions).

Only some days ago PHP.net introduced lambda functions (+ closures) are most anticipated, because they'll increase flexibility and good-looks of code a lot. Today I'm going to try to prove why lambda functions are so useful.

He looks at what lambda functions are and one of their more apparent uses - sorting. He gives an example working with information about authors and their books, sorting them by publisher and title.