PSP homebrew developer sakya has just released LightMP3 1.6.0 BETA now compiled for 3.xx kernels. Although the app won't work for M33 3.71 yet, sakya mentioned that the next version will.

Like the previous version, the newest release of LightMP3 has added some new functions and supports and also fixed some bugs. However sakya warns that the version is only in its beta version and so it hasn't been fully tested, and there seems to be a problem with USB connection. Here's the changelog for LightMP3 1.6.0 BETA:

* Added: LightMP3 is now a 3.xx application (install it in PSP/GAME3XX directory)
* Added: support to OGG Vorbis file (with streaming, so no filesize-related problems)
o OGG Vorbis has fast forward and rewind
o Note: the equalizer won't work with OGG Vorbis file.
o OGG Vorbis works fine with CPU @ 50Mhz
* Added: Now supports 8khz, 11khz, 12khz, 16khz, 22khz, 24khz, 32khz, 44khz, 48khz (both MP3 and OGG Vorbis)
o (many thanks to crazyc!)
* Added: "Repeat track" mode (old "Repeat" becomes "Repeat all")
* Fixed: volume up and down with remote controller didn't update volume bar.
* Fixed: display brightness is restored when you quit.

Users are encouraged to go through the readme file, which also contains info on the USB connection problem of the app. Note that USB connection doesn't work for this version of the app.