Annotation tables and the fact that SSAS formula engine allows non numeric measures can be a very powerful tool to show just about anything as a measure in a cube.  I just published an article that show how to put non-numeric measures in a cube using annotation tables.  The sample show you how to  display a good approximation of the last processed date of the cube or any other text you would like to display.  Using Annotation Tables in SSAS to Show Last Processed Time and Latest Data Updates as a Measure in a Cube (  http://www.msbicentral.com/Blogs/JohnHall/tabid/132/articleType/ArticleView/articleId/127/Using-Annotation-Tables-in-SSAS-to-Show-Last-Processed-Time-and-Latest-Data-Updates-as-a-Measure-in-a-Cube.aspx).