What is a deterministic wallet? It sounds as if it's a process that enables a wallet to be rebuilt from a passphrase, or from several fragments scattered about. Could someone provide a detailed technical explanation?
You've hit the nail on the head. A deterministic wallet is any system which uses a passphrase or other snippet of data to build a keypair in a repeatable manner. So long as you remember the passphrase, the keypair can be re-generated from it, so storage is no longer a security concern. There are several methods for generating deterministic wallets, but my favorite is Casascius' Bitcoin-Address generator (C#, Windows, binaries here)