The summer patch will be dropping in September sometime as confirmed by DICE. It will includes at the bare minimum:
-Night Zavod map (which looks purdy)
-More weapon balancing (goodbye death from shotty at 60m+ w/ buckshot)
-Netcode improvement (thank god)
-New team balancing improvements to public servers (Probably less continued landslide victories)
We also have a few other night maps in waiting along with the community map, and Dragon Valley. I suspect most of these are more or less ready for release, but DICE will sit on them and release them slowly in order to maximize the length of BF4. Personally I am very much looking forward to the new content, as it all looks awesome. When it finally drops expect to see me binging on the new content!