It’s the Year of the App Stores. Brands, bands and unknown developers are all busy working on the Next App.

But for how big and hip the Apple world can be, developing only for the IPhone is like making a website compatible only for one version of a browser, say Safari 4, and having a blank page for all the others. Wouldn’t it sound like a poor strategy?

That is why the IAB has decided to weigh in with a set of recommendations. And the gist of it is: stay focused on your goals, but look further than the IPhone.

So let’s look further. What do we see? Here are a few facts and numbers, collected via Distimo (a start-up active in the mobile app analytics space) and Wikipedia. Download the Distimo Report here.

STORES DNA

1) Device-Centric with two sub-categories

• Smartphones Manufacturers: Blackberry App World, Palm App Catalog, Windows MarketPlace Mobile (which will be launching in October).
• Handset  Manufacturers: Nokia Ovi Store, Samsung, SonyEricsson PlayNow, LG.

2) Carriers-Centric

• New app stores: Vodafone (by the end of 2009), China Mobile Market.
• Old-style stores- Verizon Get It Now, Sprint Software, T-Mobile web2go

3) Open Marketplace with open-source standards and an open review policy: Google Android supported by the Open Handset Alliance.

4) Closed Marketplace with propietary standards and an arbitrary review policy: Apple.

5) Independent Third-Parties Uber-Stores: GetJar, Handango, Handmark, Mobango.

COUNTRIES & REACH

World-wide: all the top third-parties stores, GetJar, Mobango, Handango. The reach is not disclosed, but the numbers from GetJar are impressive. Only last week it generated 12million total downloads (as a benchmark think that the Nokia Ovi Store has generated 10million downloads in about 3 months)!

International:

-Vodafone with a customer base of almost 300 million users in 40 countries, set to go live by the end of the year.

-Nokia Ovi Store: 109 Countries with an install base of about 100 million supported phones (but the overall potential reach is much higher, with Nokia still at a 40%+ market share worldwide).

-Apple App Store: 77 Countries with 50 million IPhone and IPod Touchs according to latest sales data

-Android Market:  26 Countries for free apps (8 for paid ones) and a 1 million customer base so far with one device.

-BlackBerry: 13 Countries and 8 million devices.

-SonyEricsson PlayNow: 13 Countries and 25 million devices.

-LG: 2 countries (not the US).

One-Country Stores: all the others.

Worth noting that China is getting into the game and the China Mobile Store went live in July, reaching a potential customer base of almost 500 million users.

POPULARITY

Apple obviously dominates with a declared 1,800,000,000 yes 1.8 billion downloads spread across its 75,000 published apps.  But here’s the rub: as Pinch Media revealed in its study a few months ago, the engagement curve is pretty low and the accelerated death of the app is an almost sure destine.

More studies have circulated since, but there’s little reason to beleive that the life cycle and exposure have gotten any better.

Developing across different platforms is not an easy challenge, inter-operability has always been The issue within the mobile industry. But following the hype (let’s get the app for the iPhone first, then we’ll see), might not be as rewarding as you might think.