Apple Unveils iCloud for iPhone

So, in other words Apple is now going to take almost all of my iPad content and send it to my iPhone and iPod. What happens when there is more memory space on one device than another? Are they going to allow me to determine how much of certain types of content goes to each device? Or do I have to run out and purchase a larger capacity iPod Touch or iPad just because my iPhone is 32GB and the other devices are only 16GB?