In fact, they've successfully released a number of custom firmware options for homebrew enthusiasts in the weeks surrounding E3. Most recently, they've released a custom firmware based on 3.52, Sony's most current release. 3.52 M33 will, once again, support the features of Sony's official release, while also launching homebrew applications. Supposedly, the latest release will also let you purchase and download PS1 games off the official PlayStation Store and play them legally on your hacked machine.
Those that want M33 on their systems must have either PSP version 1.50, or a system with Dark_Alex's custom firmware already installed. To download the M33 installer, click here. (You'll also need to download firmware 1.50 and 3.52.)
[Thanks to everyone that sent this in!]