The first version of Siaqodb has been just launched. Here you can take a look at the Silverlight Demo.
Siaqodb is object database engine that currently runs
on .NET 3.5+, Mono 2.4+ and Silverlight 3.X . As query engine it use
natively LINQ and is first database on the market that provide LINQ
query editor as default and only query engine in Siaqodb Manager
application.