I just have updated the X-loder and U-Boot on my BeagleBoard rev:C2.
These new versions:
X-Loader 1.5.1 (Oct 24 2011 - 23:55:51)
U-Boot 2011.09-dirty (Oct 24 2011 - 23:56:08)

Using the help command I have seen some new (at least for me) commands
like usb and usbboot.
Do the purpose of these commands are to support the possibility to
boot the BeagleBoard from a USB mass-storage device (PenDrive or HDD)?
Has someone already tried this, or is there any step-by-step how-to
available somewhere?

I tried to use these command according this small sentences in the in-
line help, but it does not seem enough to properly set up my board. My
pendrive was recognized and thats all. I guess I have to align the
bootargs and bootcmd environment variables to make it working, but I
have not enough knowledge and understanding of how the whole boot
process is working.

Any help really appreciated.

Thanks in advance.
Best regards,