.NET 11
Full outer joins in LINQ
LINQ gets FullJoin in .NET 11 for full outer joins
The new FullJoin method in .NET 11 returns matched pairs plus unmatched rows from both sides as (Outer, Inner) tuples. Join, LeftJoin, RightJoin and GroupJoin also gain overloads without a result selector. The feature is in .NET 11 RC2, so details may still change before the final release.