No, ZeroCoins are computationally easy to create. The concept is that you easily create a zerocoin, and then 'buy' it using bitcoins. When you buy the zerocoin, you create a bitcoin transaction, so you have to spend the corrosponding amount of bitcoins. When you want to redeem a zerocoin, you have to prove that you bought one. In this way, zerocoins are a lot like gold notes. They are cheap to create, but have value becuase they can be exchanged with gold/bitcoins, which have value and are hard to create. Unlike goldnotes however, zerocoins should be impossible to forge.