Implementing Analysis Services Process Add Functionality

I think most people who have used Analysis Services know about the ability to incrementally process dimensions using "ProcessAdd" and let's face it, without the ability to partition dimensions it's about the only data-reducing optimisation we can perform on dimensions. Sure, we have "by table" processing versus "by attribute" processing, the ability to process attributes in parallel and we can make sure that the relational layer can produce results quickly by either using snow-flaked tables or star-schema tables with indexes etc. However, we are still bound by the amount of time taken to process a given set of rows, where a subset of this information may already have been previously processed.