Oracle(originally SunMicrosystems) has added Dynamic language support in Java Runtime by introducing Groovy and GRAILS (web framework).  It is Oracle’s response to support Dynamic Language support.  

Microsoft introduced System.Dynamic namespace to support Dynamic Types in .NET 4 and also launched WebMatrix(IDE) to support development of web pages using a dynamic type scripting.  

There seems to be a huge interest in support of Dynamic types in Higher level languages. I believe that in programming languages like C# (.NET/MONO) and JAVA(JRE) where you have an intermediate layer which performs function like automatic garbage collection; the layer itself should identify the types at runtime based on their usage. There should not be much difference in performance as the intermediate layer itself has already created the performance overhead.  

It makes more sense to have a static typed model in programming language like C++, since all memory management has to be manually programmed. Now consider a dynamic language like PHP. When compared to ASP.NET and JSP, the overall memory consumption of PHP applications is far less. This just shows that dynamic programming can be more efficient as type identification and memory allocation can be performed much better by the system.

I personally believe that after nearly a decade Oracle (originally SunMicrosystems) and Microsoft have finally got it right.