To update a verygreen SASD running one of the CM7.0.x builds to CM7.1,
- Download the update for the installer/bootloader: http://crimea.edu/~green/nook/update-genimage-1.3.
- Download the CM7.1 zip: http://download.cyanogenmod.com/get/update-cm-7.1.
- Download latest gapps (not required, but a good idea): http://cmw.22aaf3.com/gapps/gapps-gb-20110828-sign
- Remove the SD from your NC and plug it into your computer
- Move the first two files to the SD card (you will only see a 100MB-ish partition; that's where they go). If both won't fit, do the installer update first.
- Confirm that the files are still .zip format (some people accidentally unzip them due to their PC settings)
- Return the card to the NC and boot into the SD's alt partition (the installer): "hold nook N key and then press and hold power until the "Loading..." message appears and then disappears with screen going blank. Release power button, then press it again and hold for ~5 seconds, the bootloader "Loading..." message should be on the screen for three seconds or so before you release power button, keep holding N button until screen blanks again. If the screen went off while you were holding the power key, that means you were holding it for too long"
- The installer will automatically install the package(s).
- Repeat steps 4-7 for the remaining files.
*For most ROM udpates on a SASD, the installer update and gapps package would not be necessary. If you're already running a CM7 nightly more recent than #86, the installer update won't be necessary. They're only needed if you're moving from a CM7.0.x stable release to CM7.1. It is a good idea to update gapps if there's a more recent package at the bottom of this page.
As of now, there is no user-friendly update path from 7.0.x to 7.1 for any SD install other than verygreen's SASD, AFAIK. In the months that CM7.1 has been under development, the SASD has become very much the standard method for running CM7 from SD on the NC. If you purchased a pre-made CM7 card, check the vendor's website for update information.