A friend forwarded me a link to an interesting blog.  In "Exalytics vs. HANA: What are they thinking?", Rob Klopp from EMC GreenPlum says that comparing SAP HANA with Oracle Exalytics is a bit of comparing apples and oranges.  These are two different products that basically do two different things (though there is some overlap when you are doing analytics).  Worth a quick read, especially the comments.