My eshop offers either 1066 memory with CL 7 or 1333 with CL9 (those are 4GB DDR3 modules). In this exact case, would you prefer frequency or latency?
For most development work (actually writing and debugging code and related tasks) it will make little difference. For relatively sequetial data access over large data sets the 1333 could feed data out faster and for more random access the 1066 with lower latency may win out.
I suspect you would be hard pressed to find many real-world examples of this making a particularly noticable difference either way though, so I would go with what-ever your motherboard manual recommends (some chipsets may consider themselves to be over-clocked running the memory bus at 1333, or might not be best placed to take advantage of the lower latency of the modules with lower bulk speed).