Whilst not being a "pro" myself I'll try to give some answers to "noob" questions in this thread.
Is it a JTAG hack?
Technically, no. But "JTAG" has come to be a synonym for the result (a completely jailbroken console), not for the technique and thus the 'noob' answer is YES
What is that about DVD keys? Can I only read my DVD key?
No. But a lot of beginners made the critical mistake of not saving a backup of their drive key and managed to lose the drive key. As a result the console was degraded to a high-tech door stopper. With the capability to read the CPU key, which requires JTAG, it is possible to calculate the DVD key and revive those useless boxes.
Can I run my backup games?
Currently, no. But the community is busily working on getting past Xell (lowlevel) and run their dashboard - including the capability to play games without having to worry about AP2.x so you can play your backups while keeping the original on the self.
What is that about a 'rebooter'?
The old JTAG method required booting, exploiting, rebooting, playing since the exploit was at a much later stage of the console bootup. This new hack is at the very beginning of the boot process (similar to before your Windows starts) and thus allows you to directly boot any software without rebooting. (At least that's what others claim But it makes sense when reading the technical aspect of the hack).
What USB/SPI device can I use except Nand-X?
Come on... Take a closer look at the adress bar of your browser.
_COULD_ it be that the 'X' in Nand-X stands for 'Xecuter'?
Segnalibri