What should I know about cloud computing?
It depends on who you are.
If you're in DevOps - everything.
If you're IT Staff - you need to understand networking: how computers communicate both within the cloud, and to your local network. VPN, routing, DNS.
If you're a CIO - Cloud Computing reduces IT staff and increases uptime. Moreover, it allows you to scale with the company quickly.
If you're a CEO - it's a good buzz word to use in your meetings.