I am using a 770 and followed the wiki for HowTo EASILY Boot From MMC card. What options should you have at the boot menu? Mine shows:
Internal flash
MMC card
MMC card, partition 2, ext2
USB hard drive
Power off (when not on charger)

Basically whats the difference between MMC card and MMC card partition2 ext2? Both boot up ok. I would guess the MMC card is the vfat partition the system is installed on but then why does it boot from the ext2 parition? Any explanation would be greatly helpful.

Nokia-N800-48:~# mount
/dev/root on /mnt/initfs type jffs2 (rw)
none on /mnt/initfs/proc type proc (rw)
none on /mnt/initfs/sys type sysfs (rw)
none on /mnt/initfs/tmp type tmpfs (rw)
/dev/mmcblk0p2 on / type ext2 (rw,noatime,nogrpid)
none on /tmp type tmpfs (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
none on /dev type tmpfs (rw)
devpts on /dev/pts type devpts (rw)
/dev/mmcblk0p1 on /media/mmc1 type vfat (rw,noauto,nodev,noexec,nosuid,utf8,uid=29999,shor tname=mixed,ro,nosuid,nodev,noexec,sync,noatime,no diratime)

By default, the bootmenu will "fall back" to the internal flash if the partition you are attempting to boot is unbootable. "MMC card, paritiont 2, ext2" is where people normally install the dual boot OS - this is the second partition on the MMC card formatted with the ext2 filesystem.

I don't know much about the second option (MMC card) - I guess this refers to the first partition on the MMC card but since this is usually VFAT (for compatability with Windows) I don't think it's very useful to you (as you won't be able to boot from it and if you try you'll boot from internal flash).

Whats the point of creating the vfat partition if the os is running from the ext2? Also is there a way to tell then what actual partition booted then since it's capable of defaulting back to the internal flash?

VFAT is there for Windows compatability - if you mount the memory card in a Windows PC it will only "see" the first partition which must be formatted with FAT.

To determine which partition you have booted from, check where your root filesystem is mounted from. In the mount command above you have this:

which means you have booted from the second partition on the MMC card (which is formatted with the ext2 filesystem). I can't remember what partition you boot from when booting off internal flash, but it might be something like /dev/mtdblock4 using the jffs2 filesystem.

As I understand the information on fanoush's website, selecting "mmc" from the boot menu scans the card for the first bootable partition. If you followed the how-to, "mmc" is equivalent to the partition2 option.

It's also possible to see all the partitions using a card reader on XP. It requires forcing a special driver to treat your reader as a removable local drive instead of usb storage. That and the lfs for windows drivers allow you to see the e2fs partition as a drive letter in XP. Now that I think of it, this method might even work directly with the IT instead of a card reader, since it also acts as a usb mass storage device. I'll have to try that soon.

Yes. "mmc" option is feature of original unmodified Nokia linuxrc script and is left in bootmenu as is. For IT2005 and older IT2006 firmware it boots from first (=mmcblk0p1) partition on mmc and there is no fallback to flash in case of failure. Since some IT2006 version it also scans next partitions (for /sbin/init executable) and selects first such one. If nothing it found then maybe it falls back to flash (not sure).