Recently, I had to create a custom component that does live filtering on data presented in a grid.
If you are reading this series, you probably know how this can be done in Flex. If you don't, a quick google search will probably point you in the right direction. Enough to say that in envolves a custom component to get the search criteria and a filter function on the grid's dataProvider ArrayCollection.
I was surprised this is relatively straight forward in GWT (using uiBinder and GXT 3.0)