The keyboard shortcut that I found is Control-Shift-M to open a box around the profile, down-enter to select "Switch person", then Tab-(Tab-)enter to select the other account. Anyone know if there's a shorter shortcut?
You can change users by clicking the top right of a chrome window.
They may not be obvious to set up, but they are worth learning about if you are going to use stick with Chrome and use multiple Google accounts, or multiple accounts on any service - Twitter, FB, etc.