How much RAM / memory does the iPhone 4 have?

How much RAM / memory does the iPhone 4 have?

The iPhone 4 has 512 MB of RAM (random access memory).

This doubles the previous 256 MB found inside the iPhone 3GS and first generation iPad. The iPhone 3G and original iPhone (2G) featured 128 MB of RAM.

The improved RAM specification on the iPhone 4 is expected to help run multitasking applications more efficiently and make it possible to render movies using a mobile version of iMovie.