From Pierre's blog today, there's this new post about some of the things that are new for GD in 5.1.x.

I brought image convolutions to the public in PHP 5.1.0 (was lying in cvs for some months already), using a 3x3 matrix, the factor and the offset. A lot of really usefull or nice effects can be realized using image convolutions. I will show you some here.

The second introduction will be available in 5.1.2, it is nothing really new and I was even sure it was already done.

Be sure to check out the post for examples of what can be done with these new, integrated features. The "Gaussian Blur" is very nice...