Downloaded and installed the new Beta version this morning. The following was working with the original Beta.
Created a ContextMenuItem with the Item containing a reference to columndata (using format [#columndatafieldname#]. Also creating a click event for the item.
When the click even occurs and is triggered on the server, the text in the events InnerHtml property contains the [#columndatafieldname#] syntax and not the actual column data. One thing to note is that the contextmenu item does display correctly when the contextmenu is displayed on the Map.
ContextMenuItem
contextMenuItem = (ContextMenuItem)e.ClickTarget;
contextMenuItem.InnerHtml