I spent quite a bit of time researching and testing various solutions in trying to preserve focus on the dynamically created control causing a postback in .Net, but nothing seemed to work, most likely due to the very dynamic nature of the page I was creating.

After thinking about what I was really trying to accomplish, I came to the realization that I was not so much concerned about maintaining focus as I was concerned about maintaining the scrolling position of the page.  After about 30 seconds of searching, I discovered a handy one-liner that solved all my problems.

Adding MaintainScrollPositionOnPostBack = True to Page_Load takes care of all of this.  So, no matter how long your page is, adding this one line of code to your page will preserve scroll location on post backs.