I learned an interesting tidbit while reading Inside Microsoft SQL Server 2005: Query Tuning and Optimization. The Max Server Memory configuration value applies to the cache buffer pool and not SQL Server as a whole. Here is a link to an MSDN article that explains it: http://msdn.microsoft.com/en-us/library/ms180797.aspx
This book goes on to discuss how to detect, measure, and remedy various forms memory pressure. I followed some of the examples in the book and came up with these statistics on one server:
One thing that is kind of interesting about these statistics is that it clearly shows that the configured server memory is significantly less than the memory used by sqlserver.exe.