Alright, I'll look into this and make sure it works. I'm currently working on Ext.List (which extends DataView) and there is still a lot of work that needs to be done on both of them. Expect DataViews and Lists to work much better in the next release.
Use dataview's itemdoubletap event. Double tap is the native dom event. Itemdoubletap gets the record and item passed to the handler. Currently the documentation lists a second itemtap event instead of itemdoubletap, this has been fixed for the next release.