I'm curious why people think the iPhone needs 1GB RAM simply because other devices need 1GB RAM or it's been the same for a whole year. The amount of RAM you need is not dependent on the competition or the Earth's revolution around the Sun, but upon requirements specific to an OS and its apps.
I've had absolutely no issues with my iPhone 4's 512MB RAM in iOS 4.0 through 5.0. I have more RAM available to the system than with any other iPhone that came before it so unless Apple has some RAM heavy additions coming in iOS 6.0 next year I have trouble believing that they will double the RAM based on the reasons in this thread.
but but you need it for True Multitasking! (been enjoying that topic on the other thread this morning).