It has been tested and confirmed that these new ocean monuments will spawn in old chunks. It can be a bit glitchy in some scenarios, but for the most part it works just fine. So with luck those of us who have oceans in our town limits will receive a nice gift in 1.8.
Sounds like there'll just be a huge pool of options you can mix and match to create a banner, rather than being able to upload a png or something whereby there would be a lot of.... explicit content banners floating around.
Made Creeper, Skeleton and Zombie Heads available in survival (they drop when killed by supercharged creeper)
Mob head items are now 3D and show the skin of the player if it is a custom mob head
Video Settings
Render distance slider now goes up to 32 when using 64-bit Java
Optimizations
Significant increase in FPS and performance
Stability in the smoothness of FPS
Chunks load a lot faster
Lighting
Completely fixed black spots
You will need to re-load old worlds for them to be fixed
F3 debug screen
Has extra information on the right hand side about your OpenGL and display
Shows a lot more values for game performance and the FPS value was moved
Regarding the optimizations... I'm on a mac and getting 60 fps without Optifine which is more than double of what I get with Optifine. On a good day. So it's pretty good.