The wildly popular photo sharing app Instagram today released a brand new version — 2.0 — that adds lots of new features, including real-time filters and higher-res images, and completely revamps its user interface.

In less than a year, Instagram has become quite possibly the most popular photo-sharing service used on iOS devices. It certainly gets the lion’s share of user buzz. Today’s 2.0 upgrade is worthy of the brand new version number, because it changes the entire base code underneath the app, giving users all sorts of great new features in the process.

The first thing you’ll notice is that filters no longer have to be applied after a photo is taken. “Live filters” let you look at the world around you through the lens of any of Instagram’s popular filters, and then take your photo. Instagram accomplishes this by making filters over 200x faster than they were before. You’ll easily be able to switch filters on-the-fly, even after your photo has been processed. Tilt-shift — the Instagram function that selectively blurs certain areas of your pictures — has also gone live as well, upgraded to perform much faster than the previous version.

Pictures are now taken at a resolution considerably higher than the 612 x 612 pixel standard that Instagram users are used to. iPhone 4 owners can utilize the device’s higher-res camera to take photos at 1936 x 1936 pixels. iPhone 3Gs owners will upgrade instead to 1536 x 1536.

You’ll also find that four new filters have been added, with more promised in the near future. Fans have long asked for the ability to turn borders on and off, and at last this function has come. Photos can be easily rotated now, and you’ll also notice a brand new UI and app icon.

Just as before, Instagram is still a free download. Also just as before, Instagram is compatible with iPad 2, but there’s still no dedicated iPad version of the app.