There are reports that Sony has already patched the Japanese version of Lumines, making it require Firmware 3.51. This prevents the Illuminati exploit, meaning no downgrading for newer versions of Lumines.

The recent Homebrew exploit called Illuminati used a save game exploit in the game Lumines similar to the GTA save game hole. This resulted in a downgrader for all PSP firmwares 3.50 and below.

Lumines has been patched fairly quickly compared to the Grand Theft Auto: Liberty City Stories, Sony is working fast to prevent more people from downgrading.

Expect to see patched versions of Lumines in areas other then Japan very soon, so if you are looking to downgrade you need to act fast.