CRM 2011 SDK 5.0.13 has been released with improvements. Here are some improvements
– ExecuteMultipleRequest. This request gives the ability to send multiple requests to the CRM service so that the requests can be executed in order without needing to come back to the client after each request. This is a significant performance boost especially when loading thousands of records into CRM. Use ExecuteMultiple to Improve Performance for Bulk Data Load
– Metadata Service. Previously had the option of returning a single attribute or entity metadata or retrieve all entity metadata. With the latest SDK, we now have the same flexibility when retrieving metadata that we do when querying records. Metadata can be filtered by entity, attribute, or even by the properties of the entity or attribute and even specifying which properties are returned.
– The Plug-in Registration tool executable file can now be found in the
Bin folder of the SDK download. The source code for the tool has been removed from the SDK download. These topics were updated to reflect that change.
– Added information about the new getClientUrl method. This method returns the base URL that was used to access the application. This is now the recommended method to use to access the organization URL. The getServerUrl method is deprecated. This method is new in Microsoft Dynamics CRM 2011 Update Rollup 12 and the Microsoft Dynamics CRM December 2012 Service Update
The above are on a high level, Download here and get into it.