As expected, smartphone giant Nokia unveiled the Lumia 610 at a press conference on Monday morning, expanding its line of Windows Phone handsets to new markets. Also, Microsoft announced a Skype Beta for Windows Phone and the pending release of Windows Phone "Tango."

"Nokia has come back with a vengeance," Nokia CEO Stephen Elop said Monday. "With great products for consumers, I think the rest will fall into place."

The Nokia Lumia 610 is aimed at low-cost Android handsets and significantly fills out the company's Windows Phone lineup. It joins the previously released Lumia 800 and 710, and the Lumia 900, which will hit US retail stores next month.

Nokia said that the Lumia 610 is based on the current version of Windows Phone, called "Mango," or Windows Phone 7.5. Tech observers had expected Nokia to announce at least one device based on Windows Phone "Tango," a minor update targeting even lower-end markets in emerging markets. And Microsoft hinted that the Nokia device was in fact based on Tango, so I'll be following up on that.

Also curious: Microsoft has no official presence at Mobile World Congress, a fact the company finally admitted in a blog post. "Rather than doing the same old trade show booth, we are taking on the competition on the show floor with our €100 challenge, Smoked By Windows Phone," Microsoft's Terry Myerson wrote.

The company did, however, finally announce a much-overdue Skype beta for Windows Phone, and the news that it would be "bringing Windows Phone to new markets and affordable new phones by expanding hardware support and regional availability." This, folks, is the Tango release mentioned above. Microsoft says that the ZTE Orbit will be available in China in the second quarter of 2012 running this software.

In semi-related news, Nokia also announced a strange, high-end smartphone called the 808 PureView that features an incredible 41-megapixel camera sensor. Not based on Windows Phone, the PureView is essentially a proof of concept that includes technologies that Nokia intends to spread into its other, more mainstream products.

"Nokia PureView imaging technology sets a new industry standard by whatever measure you use," says Nokia Executive Vice President Jo Harlow.  "People will inevitably focus on the 41-megapixel sensor, but the real quantum leap is how the pixels are used to deliver breathtaking image quality at any resolution and the freedom it provides to choose the story you want to tell."