Welcome, Cosmo! Hello from Germantown!
Although you can wait until you choose the Sony or Gen 3, be advised that e-books can also be read on PDAs, smartphones, the new iPhone... a PC or laptop... you may already have something that can read e-books, and so you can try them out before you buy your dedicated device. (I read mine on a Toshiba PDA, myself.)
In fact, the Sony reader has an emulator for the PC, allowing you to download and read e-books now... before you've even bought a reader! You can go to the Connect
site to download and try it.