I want to recommend all of Hadley Wickham's R packages, actually. Ggplot2 is one of the best R plotting packages around, easily, but --- since one of the biggest initial problems with learning R is figuring out how to use the 20-or-so built-in functions to manipulate data to the right shape --- I have to doubly-recommend Plyr and Reshape as well.
I think that's the real way to learn R. Play with it until you're thoroughly frustrated, then download a few packages like Reshape and learn them. They'll probably have better documentation and typically have some really specific use cases which will help you understand how to use R toward its strengths.
I think that's the real way to learn R. Play with it until you're thoroughly frustrated, then download a few packages like Reshape and learn them. They'll probably have better documentation and typically have some really specific use cases which will help you understand how to use R toward its strengths.