Apple has now hit the milestone 10,000th app in the iTunes App Store, and to celebrate, TapTapTap created the awesome icon tile artwork above (via TUAW), and what's more, CNBC (via iLounge) noted that Apple has snuck in some new ad copy claiming iPhone users have "downloaded over 300 million" apps.

Those numbers are simply staggering. As Steve Jobs recently, the adoption rate is beyond anything seen before in the industry. That the App Store is as unified, integrated, and easy as the iPhone platform itself is no doubt the driving factor.

But the question increasingly becomes, amid 10,000 apps, how do developers get more of those 300 million downloads for their apps?

Icon Factory co-founder and Frenzic designer Gedeon Maheux, on his gedblog, suggests that the app icon is an important place to start:

All too often icons are treated as second-class citizens, especially in the App Store. Lately, developers have taken to plastering “SALE” or “60% OFF!” within their icons. They’ve become lazy and let the iPhone software mar their design with glossy highlights which obscure efforts to brand their software. They use dull colors or pile on heaps of detail that just adds unwanted noise to an already cluttered array of choices. After the flashy ad pitches have faded, the icon still has to live on the user’s device and is often the first line of interaction with the product.

Another tool that may help is the new promo code system Apple has enabled for the (US-only so far) App Store. Erica Sadun provides a great iPhone promo code walk through over on Ars, explaining how to both give and receive, as well as some helpful hints for developers:

You can preview your Application. Once your App has been given a green light by Apple, the codes can be used—even before the release date you set in iTunes connect. Whenever your app is "Ready for Sale", Apple says you can offer free downloads. Setting a future date and releasing previews allows you to build your buzz before you go live in the App Store.

The scariest thing of all? It hasn't even been 6 months since the App Store launched (Dec. 17 will mark that anniversary). What will things look like in another 6?