In the world of Hai:You can now upload PDFs by dragging-and-dropping them onto the compose pane. The PDF will embed itself in the post, and below it will be an "Open" link that will open the PDF in a separate window.
I'm planning an update that will only embed small to medium size PDFs; large ones will just display a clickable icon (ideally, a thumbnail of the first page).
I fixed a rendering error on the front page that caused things to go out of whack. It has to do with the @ reply system. Unfortunately, @ replies don't work at the moment until I can dig into the problem. For those curious: I was using a simple algorithm to match @ symbols, which meant that if a post contained, say, 2 email addresses, the text between the two @s was rendering as an @ reply. Should be pretty easy to fix, though.