Silverlight 2 Beta2 includes a bunch of work in the
Cross Domain Sockets
Beta2 now enables cross domain networking support using both HTTP and Sockets (meaning your application can call sites other than the one
the application was downloaded from).
Silverlight will check for the existence of an XML policy
file on target servers that indicates whether cross domain network access is
allowed. Silverlight supports a new XML policy file format that we've
developed, as well as Flash policy files (which means existing sites open to
Flash can be called from Silverlight without any additional work).
Background Thread Networking
Beta2 now allows Silverlight applications to initiate
network requests on background threads, as well as process/handle network
responses on background threads. This enables a bunch of powerful
scenarios, and allows you to avoid blocking the browser's UI thread while doing
both HTTP and Socket network communication.
Duplex Communication (Server Push)
Beta2 enables support for setting up duplex communication
channels with a WCF service on a server. This enables a clean programming
model that allows servers to "push" messages to Silverlight clients
without the developer having to manually poll servers for changes. This
programming model is very useful in a variety of scenarios, including instant
messenger/chat applications, and monitoring/update applications like stock
tickers and trader applications.