It was 2009 MWC, when Microsoft had launched Windows Mobile 6.x Marketplace, it had allowed so many Windows Mobile 6.x users to download apps, games and lots of other thing to their mobile phone.
As Microsoft has now launched a separate marketplace for their latest mobile OS, Windows Phone 7, they had decided to discontinue the old marketplace, and they will close it on 9th May, 2012.
Onward of 9th May, 2012 you wont be able to download or access your Windows Mobile 6.x marketplace, it may be noted that WP7 marketplace wont be affected.
If you are using Windows Mobile 6.x device then it is recommended that you update your any current apps to latest version. After the closing of Windows Mobile 6.x marketplace you can still download and install which supports your device from developers website or from any 3rd party marketplace.