In the ClientUI control sample, we are downloading another XAP file.

Loading another XAP in SL page is supported in ClientUI, this topic has been discussed in detail in the ClientUI documentation on the article "Application Framework Overview". The article is already available online here.

Thank you Glenn; I found the material to read.

This is a very powreful feature. Have been discussing this with Jimmy!

..Ben

Glenn, I haven't gotten to the full detail of this feature yet, but let me ask you another related question. When using assembleies, do they have to be created by the same developer that created the shell or could these XAPs be someone elses XAP that the UXShell can load and run?

Thanks!

Based on the documentation, in order to load external XAP you will need to create ApplicationPackage object and and set the source property to the external XAP. It should not matter if it is created by the same developer or not as long as you could set the correct URI to the XAP.