This is the final iR Shell public release as coder Ahman is retiring from the PSP scene.

Changes:

Added support for 3.80M33-2, M33-4 & M33-5. Pls note M33-1 & M33-3 are not supported due to some technical issues which I’m lazy to resolve.
Added support for 3.80 Popsloader Version 2. Version 1 isn’t supported.
The 1.5 Kernel Addon for 3.71M33 & 3.80M33 has caused some incompatibility issues with fw 1.5 iR Shell. This is now resolved.
Enhance PSP ISO compatability. Previously failed ISOs will probably work in this release.
For slim only, the nethostfs MAX mode is now compatible with WPA.
Some older firmware supports have been removed to reduce the distribution archive. This version has support for fw 1.5, 3.10 to 3.80. Also, directories EXTAPP15 & EXTAPP3X have been combined into a single EXTAPP to save space. Each APP# directory has 2 EBOOTs, with EBOOT.PBP for fw 3.x and EBOOT15.PBP for fw 1.5.

http://irshell.org/showthread.php?tid=1094