A summary of what I know from California zoos:
Los Angeles Zoo: They are finishing up a long-in-production master plan that has reshaped a good chunk of the zoo. Since 1998 there they have built new chimpanzee, orang-utan, gorilla, seal, and Asian elephant exhibits; a new reptile-invertebrate complex, a new entrance complex and education building, repaved the parking lot into a "green" lot that collects water run-off and channels it into the local aquifer and is landscaped with California native plants. They are currently building a "Rainforest of the Americas" that will feature giant otters, Baird's tapirs, harpy eagles, red uakaris, and other species not yet revealed. Hopefully a new wave of projects will follow in coming decade as there are many major exhibits that need replacement still (lions, hippos, giraffes), etc.
San Diego Safari Park: supposedly they are going to begin work on the new tiger exhibit complex soon which will feature Sumatran tigers and several Asian bird species, but they have been talking about building it for years so believe it when you see it.
San Diego Zoo: new koala and other Australian animal (possibly Tasmanian devils and wombats) exhibit complex is under construction. They just opened a newly renovated Reptile Mesa. Rumors are that the old grottoes and cages in Cat Canyon will be replaced by a new Africa exhibit of some kind, possibly including African penguins. Penguins have been absent from the zoo since the 1970s.
Living Desert: Rumors are that they are gearing up to build their long-in-development lion exhibit in their Africa area. In past plans this area has also included black rhino, baboons, and Nile crocodiles, but unclear if this is still the current plan.
Oakland Zoo: they are building a new animal hospital and then their long-in-development California area that will feature grizzly bears, wolves, California condors, mountain lions, and jaguars. Not sure what other species will be included. Beavers and black bears were also in the plans at one time.
San Francisco Zoo: new polar bear exhibit to replace the old bear grotto, new big cat exhibit complex, new great ape complex for chimps and orangs, new rhino and hippo exhibits with underwater viewing for hippos, renovated gorilla forest, and rumors of new elephant exhibit down the line...NOT. Supposedly they are building some new playgrounds, a squirrel monkey exhibit, and a new cage for their bobcat. Yippee.
Aquarium of the Pacific: just opened a new magellanic penguin exhibit.
Sea World: new roller Manta coaster and non-manta ray touch tank
Fresno: new sea lion exhibit opening this fall or soon after; new Africa exhibit for 2014 with African elephants, lions, white rhinos, spot-neck otters, giraffes, etc. These developments may be the most exciting California project as they have a lot of money to build with, an ambitious director, and a supportive community.
Sacramento: new monkey and gibbon complex in near future are rumored. They just got Wolf's guenons so would assume that they will get a new exhibit soon.
Sequoia Park Zoo in Eureka (only AZA zoo in California I've not yet seen): new river otter-salmon-bald eagle exhibit...sounds quite cool. They have an ambitious master plan to rebuild their small zoo and seem to be making good progress from what I read. The master plan is on their website.
Micke Grove Zoo in Lodi: lost AZA accreditation in 2005ish. Working to get it back. They have plans for and have partially constructed a new snow leopard-Asian small clawed otter exhibit complex and hopefully can finish it.
My two cents:
