Few months ago Microsoft has announced about its new mobile platform: Windows Phone 7. And here the pursuit started. Thousands of developers started looking into it to develop something new.
The same way I did. Decided to start from scratch a month ago - to develop a simple Tetris game. First I've investigated the market - there were several such games, but all had very small playground, which was not user friendly (by me). So the core of my idea was to make the playground as much, as the phone screen is.
Microsoft did really good job by creating a lot of restrictions for the apps, which you are going to expose on the marketplace. There is a big doc of guideance you have to follow.
After few days of development, when I had the game skeleton ready, I've started investigating the way to publish it. First I had to register withing the AppHub( this costs 99$). After the registration (which is not available for any country) I had to wait two weeks to be validated. One of those validation points being handled by GeoTrust (a partner company responsible for registrant validation), and this was the longest part to wait for.
Registration is done, and the only step left is to wait until Microsoft verifies your application. This stage took them only a day. And finally, my app is on the marketplace. This is the start, and it was really easy. So I will continue my app development for WP7 - for a great mobile platform.