sample implementation of a recursive (indirectly speaking) SymbolVisitor for Roslyn CTP. Returns flattened list of type symbols regardless of namespace nesting

RecursiveNamespaceVisitor.cs

    public class Walk : SymbolVisitor<NamespaceSymbol, IEnumerable<NamedTypeSymbol>>
    {

        protected override IEnumerable<NamedTypeSymbol> VisitNamespace(NamespaceSymbol symbol, NamespaceSymbol argument)
        {
            var types = new List<NamedTypeSymbol>();

            foreach (var ns in symbol.GetNamespaceMembers())
            {
                var closeTypes = types;
                closeTypes.AddRange(Visit(ns));
                closeTypes.AddRange(ns.GetTypeMembers());
            }
            return types;
        }
    }

/* and a quick self-standing unit test (xUnit) */
    public class TypeSymbolWalkerFixture
    {
        Walk sut = new Walk();

        [Fact]
        public void when_walk_nested_namespaces_with_types_returns_all_unnested_classes()
        {
            var code = @"
namespace Bar { 
    public class FooA {} 
    public class BarB {} 
    namespace BarB { 
        public class FooB { public class NestedFoo {} } 
        public class FooC {}
    }
}";
            var tree = SyntaxTree.ParseCompilationUnit(code);
            var comp = Compilation.Create("testA.dll").AddSyntaxTrees(tree);

            var result = sut.Visit(comp.GlobalNamespace);

            Assert.NotEmpty(result);
            Assert.True(result.Count() == 4);
        }
    }

added tweaked code + a test to prove functionality