I do not recommend to try it without a flasher installed and a dump of the flash.
To quote, roughly translated: Hi all, What better than to come back with this kind of news! Our friend and SGK developer releases today the result of hard work. Indeed, in the shadow he worked to bring us a CFW with features interesting and not yet seen the new CFW 4.xx
The basis of this CFW is based on Rogero 4.30 and the 4.21 Rebug CFW which is the most stable and most successful of the moment. He added SGKXMBM + Package Manager for our greatest pleasure. Some files from firmware 4.31 which ensures compatibility for the latest keysets. So you can play your backups favorites without a patch or fix. 4.31 is a spoof includes access to PSN and avoid unintended updates.
Added package SGKXMBM +
Lv1 Lv2 and recompiled.
Patched Peek & POKE
Coldboot game replaced
Theme changed from dynamic watch dogs
Testers and developers: consolehackdev / ZZ / dedalo! Teamsgk/ps3devs; SGK_84
Stay tuned for more PS3 Hacks and PS3 CFW news, follow us on Twitter and be sure to drop by the PS3 Hacks and PS3 Custom Firmware Forums for the latest PlayStation 3 scene updates and homebrew releases!
To quote, roughly translated: Voilla my new cfw 4.40.5 available in the day with a great new mode 3 the normal 4.40, 4.40 CDEX the fashion and fashion DEX 4.30!
New icons by Hackxell.
Improved support to Rebug Toolbox for all modes of the CFW (normal, CDEX and DEX).
Added PSIDPatcher 4.40 Rogero style.
Access to the PSN (normal mode).
ReActPSN fully functional (normal mode).
Fixed the error at startup of the Minis games that displayed a black screen.
Coldboot Minis replaced.
Can be installed by all cfw (3.55, 4.21 to 4.30 and to 4.40), is not installable on consoles with OFW greater than 3.55.
Set "System Update Debug" ON.
Copy the. PUP in the usb drive that you prefer in the usual path PS3/UPDATE.
Start it from XMB starting from CFW (3.55, 4.21 or 4.30)