Depends on how you define a "leak." .NET (and i think java???) waits until an allocation request fails before it collects any garbage. As a result, long-running .NET apps tend to fill all availiable memory and swap before stabilizing their memory usage. (i'm thinking of SharpDevelop in particular, there aren't many other large .NET apps out there)

And I don't have to remind anyone who uses Windows, the OS doesn't behave well at all when its main memory and swap are filled. So in my opinion, having long-running managed apps makes for a much worse interactive user experience.

tangentially, remember that longhorn is planning to move many more shell programs to managed code...