Fantastic. From poking around in the console a bit, it looks like Do.com is a Backbone.js app, and is using Handlebars.js for templating.
What you see is just the beginning. If anyone's interested, we're hiring developers and designers: http://news.ycombinator.com/item?id=3060989. We run as an independent business unit within Salesforce, similar to Heroku, and have our own office in downtown SF. Great perks from a large company but all the benefits of shipping as a small team.
Been using Asana about a week now so here's some comparisons:
* I like that less is happening on hove compared to Asana—I find the over-reliance on hovers and background changes (cf. new Twitter) very distracting
* the notes idea is cool
* You have the same issue Asana has with "groups"—can't drag a group together
* I prefer Asana's ability to rely on the keyboard heavily
* You should add drag/drop for file uploads, at least using the right pane as the target. I work on a 10yo application so I know why we don't have it but with apps like this it's a no-brainer. It would also improve the upload flow which I dislike, though Google Docs integration is great.