My son went into the Navy 6 months ago. I have his portrait pictures from Boot Camp in his "Crackerjack" uniform. When I went to Boot Camp graduation in September they had the choice of wearing long sleeve or short sleeve White's. (Great Lakes) He is now stationed in Guam so they wear White's all year round.
This is all about to change. The Navy is changing from Summer/Winter uniforms to year round uniforms. The "Service" uniform wil be black pants with a Khaki shirt all year round. The "Work" uniform/jumper will be camouflage like you see the men and women wearing to Iraq. The Navy will have blue/grey/white in the digital camouflage.
The single service uniform should save costs on uniforms and packing/storage. The camouflage is to hide imperfections created while working (dirt/runs). Should last longer.
Look at
http://en.wikipedia.org/wiki/Uniforms_of_the_United_States_Navy PS: My Dad (Armed Guard) ran the Navy Uniform Shop and Warehouse from 1963 until 1996. If you got a Navy Uniform or Accessory in those 33 years it went through his department.