I'm creating a line of business application using Silverlight 5.
The application is really be great using MEF as a Dependency container. I'm worry because I have to put this LOB application into some tablets like Nook B&N Tablet, KindleFire.. and I've seen that this tablets are not compatible with SL5.
I don't plan to rewrite all the program, but what alternatives do I have to do this?
Not an ideal solution, but your best bet if you don't want to rewrite your complete application is to look into Mono for Android which runs well on Kindle Fire and should do the same on the also Android based Nook.
AFAIK you'll need to rewrite your UI pretty much completely for Android since XAML isn't supported, but much of your business related logic should be reusable.