Q. My CPU and Memory indicators are missing in Ubuntu 11.04 under Unity. Is there any way to get them back?

A. No, not the one that you are used to, but here's one for Unity specifically. It doesn't have the nice graphics, but it'll do what you want.

sudo add-apt-repository ppa:alexeftimie/ppa
sudo apt-get update
sudo apt-get install indicator-sysmonitor

Once installed, it can be activated from Applications → Accessories menu