At MWC Microsoft announced that it would shortly be making the Windows Phone Marketplace available in an additional 23 countries. The Windows Phone Developer blog notes that submission for these Marketplaces will open shortly and there's "a great opportunity to establish an early toehold on top download charts". 

The new Marketplace countries are 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. They will take the total number of Marketplaces to 63, of which roughly half are new in 2012.

Developers can take advantage of the new distribution opportunity by visiting App Hub and updating the markets where there application is available. This step is necessary even if worldwide distribution has been previously selected. A number of the new markets (Bahrain, China, Indonesia, Kazakhstan, Malaysia, Qatar, Saudi Arabia and the UAE) have additional requirements due to local regulations.

The blog also notes that, due to to the volume of app submissions and updates, it is currently taking 7 days to certify an app (to go from submission to published). Something that developers may want "to consider if you’re aiming to have your app live by a particular date".