Microsoft is running a promotion for Marketplace developers to encourage more app submissions. Microsoft is giving away 5 Samsung Series 7 Windows Slates to developers submitting apps, with each submission counting as an entry to the contest.
Developers who submit more than 5 apps stand a chance of one of their apps wining free advertising on the Windows Phone app network (up to 25,000 impressions over 60 days).
Developers who use Azure with their apps will have a further bonus entry.
The contest runs until the 31st December 2011 and is open only to US residents.
Read more about the promotion at WindowsPhone7event.com here.