In this new post from Harry Fuecks on the Sitepoint PHP Blog today, he talks about the pecl_http package and how it can boost PHP's HTTP abilities even more.

If you’re looking for 15 minutes diversion, pecl_http is worthwhile, in particular the tutorial.txt file that comes with the download.

Basically gives PHP a serious HTTP boost. Some particular things it does: adds functionality for outgoing calls that would normally use header(), provides amore-friendly cURL wrapper, allows the creation of a HttpRequestPool, and includes HTTPResponse functionality that helps with some of the caching...

There's a bit of code to show how to work with that caching previously mentioned. It's not available on the Windows package site, though...