Counternotions offers iOS clipboard history as an interim solution for proper, elegant multitasking:

But until Apple has a more general solution to multitasking and inter-app navigation, the four-unit clipboard with a visible UI should be announced at WWDC.

I started using Jumpcut, a Mac clipboard history add on a few years back. It's the single most helpful app I use and surprising that Apple hasn't replicated this functionality in OSX as they have with other add ons like Growl and Quicksilver.