One big factor in this is the Enterprise. An Enterprise is a company or business, usually, but not necessarily, of a large size. An Enterprise will have thousands of employees, working at different locations, sometimes around the world.
Enterprises like Intranets – internal browser based communication systems. Enterprises like browser based applications that run on these Intranets because they are easy to distribute and maintain.
Employees of Enterprises work on clients (PCs, laptops, etc.). These clients are owned and maintained by the Enterprise, i.e., Enterprises can install whatever they want on their client machines – see I told you we’d come back to the client thing – and have the processes in place to do this regularly and en-masse.
The take of up SL, and FLEX to a much lesser degree, within these types of organisation is massive, especially in the banking sector who rely on rich, interactive applications (my version of RIA). Other technologies just do not cut the mustard. This is a FACT!
SL has a great advantage in these types of organisations who are mainly .NET based organisations – there are a lot of JAVA based ones too, who would probably have used FLEX rather than SL: SL sits nicely in their application stack.