Well, today is the big day. Diehard Apple fans around the world are either enduring endless lines or eagerly awaiting the UPS truck from the comfort of their own home. They're all doing the same thing: Pulling open that pristine, white packaging to reveal the latest coveted gadget from Apple's overseas factories: the new iPad.

Apple isn't the only one that's been busily prepping for today. App developers everywhere have been recoding and resubmitting their work to the iTunes App Store to take advantage of the new device's specs. More than anything else, it's the iPad's super-high resolution retina display that's giving developers the most compelling reason to push out an update.

With its resolution of 2048 x 1536, the iPad's retina display can make even the most well-designed apps look dramatically better. The screen, as Tim Cook proudly pointed out, has 1 million more pixels than an HDTV set. Naturally, any app that puts a strong emphasis on its visual appearance stands to gain in terms of design aesthetics and user experience.

Enhancing Games and the Reading Experience

A number of popular apps have already pushed out updates. One of the categories best-suited for the retina display is, of course, games. That's why Apple demoed Infinity Blade II during the iPad's launch last week, which by all accounts looks stunning on the new device. Other iPad games that have been updated in the last 24 hours include Labyrinth 2 HD, Modern Combat 3 and Mass Effect Infiltrator.

Besides gaming, one of the activities people do the most on their iPads is reading. The developers of some of the platform's most widely used reading apps wasted no time ensuring the experience on the new iPad lives up to its potential. Amazon optimized its Kindle app, as did Readability, the Instapaper-style, clutter-free reading app that just landed on the iPad two weeks ago. Popular news apps like The New York Times and The Daily are ready to go with sharper text and richer graphics, while Flipboard, the frontrunner in the personalized, social magazine space, just got even prettier.

Some other newly-updated iPad apps that have been well-received include Evernote, Tweetbot, Mint, Skitch and Sketchbook Pro.

Optimizing For the Retina Display: What's Involved?

While a small flood of app updates have come out over the last 24 hours, the new iPad has only been in people's hands for a less than that, so we should expect to see many more apps get optimized in the weeks to come.

From a development standpoint, making one's app retina display-ready is fairly straight forward. It's mostly just a matter of including higher-resolution graphics and, when applicable, enhanced video content. This process can be a little more intensive for apps that are heavier on images and animations.

For iOS developers who have already put in the work to update their iPhone apps to look great on the iPhone 4 and 4S, much of the hard work is already done. Text-based content translates pretty well to the retina display on its own.

"Eventually, every app will need to be retina compatible," said Jonathan George, CEO of Boxcar, a push notification service that is about to release an update to their iPad app. "When we transitioned from the iPhone 3G to the iPhone 4, users complained about how "ugly" the apps were until each app transitioned."

Optimizing for the iPad's new high-resolution display is well worth the effort for developers, but it doesn't come without its drawbacks. The most widely-discussed drawback is the increase in the overall size of the applications. Some apps have seen massive jumps in the amount of space they take up on the device. The extent of this issue truly depends on the nature of the application and how graphics-intensive it is, but in many cases the size of app can double or triple as a result of being optimized for the retina display.

Another, albeit much smaller, frustration is waiting on Apple's approval. "I'm disappointed that our update is not out on the first day of availability," said Ryan Kairer, who recently submitted an upgrade to his MacHash News app to the iTunes Store. "I submitted updates for my apps six days ago and they are still in the queue."