Just to make this clear for everyone, the 511EB does not currently support the Memo function for note taking.
If you look at the quick start guide that came with the ebook reader the second page shows you the menu layouts for both the 511EB and the 511tEB. The touchscreen version has 8 menu items, the 5th one being for ‘Memo’, 6th for ‘Tools’. The 511EB currently has neither of these menu options.
The keyboard is still useful for book title searching, bookmarking and searching for text in certain e-book formats. The text search and reading function definitely works within .txt and .html files although not in .epub (just option to bookmark in the menu).
Hope this helps to clarify the situation with regard to use of the keyboard for taking Memos.