If you click on your own name and then click on "saved stories", in theory it shows you stories you upvoted. Mine is currently blank:
http://news.ycombinator.com/saved?id=Mz
I have seen others report problems as well. So I don't rely on that supposed feature.
I noticed today that my submitted stories page shows upvote arrows for my older submissions (as if I hadn't upvoted/submitted them). Only the 20 first ones have the red asterisk. And my saved stories page does not show old stories.
So it's not just me. Just to make sure, you know that link only works for yourself, each user can only see his own saved stories page.