To go along with the new hardware and software being announced at MWC, Microsoft are expanding the Windows Marketplace, adding 23 countries to take the total worldwide market count to 63. But the big change, ensuring that the new lower specced devices will still be able to benefit from as many of the apps in the marketplace is under way with the launch of a technical preview of an SDK Update so developers can test their code again the new hardware footprint.

First up, Joe Belfiore talks about the countries, market, and how many more customers Windows Phone will be able to reach:

We recently enabled Windows Phone Marketplace in Argentina, Indonesia, Malaysia, Peru and the Philippines. Today we’re announcing that in the coming month we plan to extend Marketplace to customers in 23 more markets, including; Bahrain, Bulgaria, China, Costa Rica, Croatia, Estonia, Iceland, Iraq, Israel, Kazakhstan, Latvia, Lithuania, Qatar, Romania, Saudi Arabia, Slovakia, Slovenia, Thailand, Turkey, UAE, Ukraine, Venezuela and Vietnam.

That’s 28 new consumer markets this year alone, for a total of 63 markets worldwide where your Windows Phone apps may be sold. In terms of actual potential app customers, the addition of new price points and customers in China and the other new markets represents a near 60% increase in the total addressable market for Windows Phone. I told you it was a big step!

Microsoft have been proactively reaching out to developers who, through the anonymous collection of usage data, who have applications that will nto work in the smaller memory footprint. Belfiore writes that around 5% of current applications will not run and have been marked as such in the Windows Marketplace. Developers can tweak their code and change the manifest file value back to 'it will work' and make it available to devices like the Nokia Lumia 610.

There are far more details in the blog post, so you should head over there to see how it's all going to work.