In Fanoush's description of how to install the hacked OS for higher MMC transfer speed (http://fanoush.wz.cz/maemo/#mmcplus) he says

"I suggest you first boot it via 'flasher-2.0 -l -b -k zImage-su-18-200625-2gb-mmcplus52Mhz' and test all your cards before flashing permanently.
If it works you can flash it via 'flasher-2.0 -k zImage-su-18-200625-2gb-mmcplus52Mhz -f -R'.
If you are sure you want to flash it without testing and prefer flashing directly from the device without using USB cable, you may try my kernel flasher above."

I'm confused by this. I have copied the stock 2006 OS to my 1GB MMC card and now have several boot options on cold start:

Internal flash
MMC card
MMC card, partition 2, ext2
USB hard drive

The 1st and 3rd I understand, "MMC card" don't know what that's for, does the 4th mean I can boot via USB from my PC's HD? I tried googling for more info and get hints that yes, it's possible; there's a page of incorrect info out there somewhere.

If there's a page of correct info somewhere I'd love to see it. The notion of trying a hacked OS before flashing it sounds great to me.