When Should Namespaces Become Their Own, Independent Class Libraries?

I could use a little advice on naming my assemblies (ie. When to turn a logical naming convention in my namepaces into its own DLL).

I recently downloaded an example project with a ton of class libraries in it that almost exactly mirrored the namespaces.

To date, I have been building one massive class library - MyProject.DLL - and referencing it in my project. This way, I only need one library and can access all namespaces using it.

But, in the project I downloaded, there seems to be a DLL for every namespace (and, in some cases, subcategoreis within a namespaces. For example, SomeProj.Web.Security has SomeProj.Web.Dll and SomeProj.Web.Security.Dll).

I understand that having multiple DLLs can make it easier to focus on particular areas of the project (and, probably, updating 开发者_运维百科the DLL withing the site easier) but is there a best practice here?

Thanks in advance...

OK, this pretty much answers my question:

http://msdn.microsoft.com/en-us/library/ms229048.aspx