Here's what it looks like now: https://dl.dropbox.com/u/4595/hn-vote.png
Suggestion: For UI consistency, I would put the upvote for stories on the left of the title, in the same spot it is for comment upvotes. It might just be a personal taste thing, but I could see myself downvoting something on accident, by pressing the button where the submission upvote usually goes. I like that the up/downvote buttons are on opposite sides of the comment. It should keep fat fingers from miss-voting.
If you haven't seen that feature of Tweetie 2, it's awesome. It embeds the tweet itself, along with any relevant links, in an html email. Oh, and most importantly, sending the email doesn't require you to quit the app.
I suppose you'd be embedding the story title, description, a link to the HN thread, and of course, the link to the original story.