I have noticed a few small glitches.
The paging grid example that is set as sorted by last post desc takes two clicks to change the sorting on that particular column. It seems that the first click goes to the server and sorts it desc which in essence changes nothing (since it was already sorted that way), then the second click works as it is supposed to (changes the sort to asc).
The other oddity I noticed involves holding the shift key while arrowing up or down on the grid while in single select mode. The grid still only allows one row to be highlighted, but after selecting some rows with shift held down then releasing the shift key, the selection will go back to the original row selected. It seems that only the visual aspect of single selection occurs while behind the scenes you are still selecting all the rows. I have not yet tested to see if the grid thinks just one or multiple rows are really selected. If that is the case it would be bad, otherwise this is rather minor.
BTW great job Jack. I have been following ext for sometime, I've just now gotten around to playing with it though. I look forward to future releases.