Breaking News! It looks like you really can buy gift cards at Best Buy for Connect ebooks.
From a very helpful gal at Sony Connect support. Check out the
front page post.
I'm surprised they aren't shouting it loudly to all Sony Reader buyers. Sounds very convenient. Just in time for Christmas also! ;-) Maybe that's a stopgap plan, and they really prefer people to buy gift cards in other ways in the future. After all, if you get a Best Buy gift card, there's always the chance you might spend it on that other electronic gizmo you've been wanting!
UPDATE: This information seems to have been incorrect. I wonder if those gift cards are taken in the music store. That might have been a source of confusion for the Connect support people.