Get ready guys, it's open season again. No, not for hunting, but emulating. It appears that a crack has been found in conjunction with the popular PSP puzzler Lumines that will allow homebrew and custom firmware on all current released firmwares on the PSP.
The homebrew community is significantly larger than expected. Lumines sales absolutely exploded, raising 5,900% on Amazon.com since this exploit was discovered. Prices were as low as 5 USD on eBay previously, but now you'll be hard-pressed to find a copy under $15.
Sony will surely "fix" this with a new firmware update, but for now, get cracking!