In SSAS 2005+; you can link dimensions as well as measure groups from a source cube to a linked cube.
 
However, if you go back to the source object and alter it, the changes will not be reflected in the linked cube unless you delete the object and add it back. Doing this can be time consuming and dangerous as you also will have to remap the dimensional objects.
Since the linked cube is just basically a metadata point in time capture. It seems that something could be programmatically built to identify the differences and update the .xmla code for the linked server. like a "Refresh Linked Objects" button.
 
I've tested this by doing a view code of a linked cube before and after I added a new dimension to a source cube with 1 attribute. Once I removed the old linked measure group and readded it, the new dimension shows up in the linked cube. When I viewed the
code of the linked cube, I found that it added 40 lines of .xmla. Seems that this should be pretty easy for you guys given that some of the stuff BIDS helper does is absolutely AMAZING :)