I found out how you can upgrade the Nokia 770 Internet Tablet's internal memory by extending the root filesystem to a memory card. My step-by-step guide with detailed instructions has been posted on the Maemo Wiki. Following the steps, one can expand the unit's memory, make it persist even through flashing, and protect the internal flash memory's durability all at the same time. All power users are welcome to check it out and see if it helps them to get even more out of our favorite Linux device. Here's the link: http://maemo.org/maemowiki/ExtendedRootFilesystem