From the Instapaper blog:
“When the [Betaworks] team sat down with Instapaper’s creator, Marco Arment, back in April to get a download of his ideas and to-dos for improving Instapaper, the first thing on his list was to update the Instapaper website. Well we’ve done it, and it’s now ready for you to check out and test.”
I've only been using the beta for a few minutes, but I already dig the new visual style and layout. It's very exciting to see that Instapaper's still being actively developed and improved after Marco sold it a while back.
If you'd like to check out the beta, just head over to beta.instapaper.com and log in with your Instapaper credentials.