ObjectDataSource Cache

Each ASP.NET application has its own data cache instance that’s shared across all pages and visitors. That means that the data stored in the data cache by the ObjectDataSource is likewise shared across all users who visit the page.

http://www.asp.net/learn/data-access/tutorial-58-cs.aspx

Using SQL Cache Dependencies
http://www.asp.net/learn/data-access/tutorial-61-cs.aspx