So boys and girls, the lesson here (for folks who'll read this thread three or four years from now): yes, old yeast is usually perfectly fine to use. They may, however, require some extra time and a little love to get going. Earlier this week I started a starter for some WLP007 that I harvested and put in the fridge back in April (almost nine months ago), and as we speak I've got a 1.5L starter of the stuff that's going to go into a batch tomorrow. It's all about patience, and stepping up your starter gradually. The yeast will (almost always) come back!