I'm suspending my "weekly" Agent Updates for a while. Honestly, other people/sites do it better than I do. If I see value, I'll resurrect my updates. However, I plan to revise my Searching for Literary Agents blog post in the next few weeks, which will list all the good current sites to use in your agent search. For now, here are the primary sources who report agent changes and moves:
QueryTracker.net - New and Updated Agents
AgentQuery Connect - Agent Updates
Publishers Weekly - you should sign up for FREE subcription to PW Daily.
There are many other sites as mentioned in my Searching for Literary Agents blog post to search for agents, but the sites above actually post changes on a daily basis.