Nokia Lumia 900 to hit AT&T on April 8. But what about apps, updates?

Nokia officials are confirming that leaks tipping the arrival of the Nokia Lumia 900 on AT&T on April 8 for $99 are correct.

Nokia's flagship Windows Phone (codenamed "Ace") will be arriving in the midst of new questions from both Windows Phone advocates and critics about Microsoft's longer-term strategy and direction for the platform.

AT&T, which has evolved to become Microsoft's premier U.S. phone-carrier partner for Windows Phone, is dragging its feet about providing users with the 8170 "disappearing keyboard" update from Microsoft. Microsoft officials originally were on record saying that carriers could only block one update. More recently -- and not too surprisingly -- Microsoft execs  acknowledged that carriers can decide to deliver as few updates as they want (though if and when they ever do provide them, those updates will be cumulative).

This situation is making for some unhappy early Windows Phone adopters. (Me? I'm one of those stuck on Verizon, which hasn't rolled out this update, or another Windows Phone beyond the HTC Trophy in the spring of 2011. So my expectations as to Verizon's Windows Phone commitments already were low.)

Meanwhile, on the app front, at least one Silicon-Valley-centric pundit is claiming that Windows Phone's 70,000 available apps are too little too late -- regardless of how soon Microsoft reached this milestone vis a vis Apple and Android.

The Windows Phone marketing team knows all too well they need to change the app conversation. On March 26, Microsoft and Nokia announced each company would invest up to 9 million euros ($12 million each) into a newly established mobile app-dev program at Aalto University in Finland over the next three years. The program is designed to help create "innovative mobile applications for the Windows Phone ecosystem and in addition, Nokia platforms, including Symbian and Series 40, to create a new generation of self-sustaining mobile startups."

But there's more coming on the app front, if Microsoft is sticking to its own December 2011 Windows Phone Marketing playbook, that is.

Microsoft has some aggressive plans to promote apps from vendors which compete with those from developers who are not creating Windows Phone versions of their apps. The slides from the U.S. marketing playbook (a few of which I'm including here) mention a $10 million campaign over three years to "ringfence" companies like Pandora which aren't supporting Microsoft's platform.

(Note: "BG" in these slides means "business group.")

Microsoft also has plans to try to turn the app conversation from "quantity" to "quality," especially on the Android vs. Windows Phone front. (RSP = retail sales personnel.)

The company also is lining up more promotional opportunities for top Windows Phone apps and to make use of "app cards" as an enticement to new Windows Phone purchasers.

What do you think, Windows Phone fans and foes? Is Windows Phone on an upward trajectory? Or looking stuck in a distant fourth place?

Update: Here are a few additional details about AT&T's April 8 plans from a blog post by AT&T officials.

The same day that Nokia Lumia 900 launches on AT&T for $99, the HTC Titan II also will launch on AT&T for $199. And the Lumia 900 will be available in white (in addition to blue and black), but the white phone won't be out until April 22.