Today I got the chance to make use of Jim Ross's excellent article, “Maintain Scroll Position in Any Page Element”. It describes when using a scrollable Datagrid--one inside an overflow-auto DIV control--how to maintain the user's scroll position inside the DIV across postbacks, such as when a Select button is clicked. It does this using IE behaviors, HTC files, which I hadn't used before, so that was fun, and it also solved my problem.
I also liked the ReadMe.txt that came with the sample downloaded code: “The sample application is written in VB. If you only know how to read C#, stop whining and learn to read another language. It will be good for your soul, and your career.” :)
P.S. Jim also has a new article out about Datagrids and ViewState, check it out.