The Java world has portal standards called WSRP and portlets. Major Java portals seem to support it. It allows you to write a portlet using web services and defines standards for local portal component behavior. It's high time the .NET world adopts some standards in the portal market segment.
For example, if I want to write a component to a .NET portal, I need to choose if I am going to support Sharepoint, Dotnetnuke, Rainbow, etc. I cannot write a portlet that works in multiple .NET portals. This hurts the small ISVs that make money writing portal components as they have to choose which portal to support. It also hurts portal administrators as it limits their choices.
ASP.NET 2.0 supports web parts which could be used as a basis for .NET portlets but the portal vendors work together to build a standard that works. If you are a portal administrator or portal component vendor then you should start pushing your vendors to work together to build a common portlet standard for ASP.NET.