The workshop will be held in July, so it'll presumably be hot and humid; expect daily highs somewhere between 80 and 95. However, the rooms where we'll spend eight hours a day are air-conditioned, so you may want to bring long-sleeved shirts or even a sweater. It may well rain, so bring an umbrella.
We'll be holding the workshop in a computer lab and a "break-out room" in the Swirbul Library. The computer lab is all-Windows, but the software runs equally well on Unix, Windows, and Macintosh. If you prefer to bring your own laptop (Windows, Macintosh, Linux, whatever) and work on it, that's fine. I encourage you to download and install the DrRacket software before you arrive.
The main textbook we'll use is my Picturing Programs, which is available for free on the Web and in paperback for about $30. Again, I recommend downloading it and starting to read it before you arrive. You don't need to bring other Scheme texts or references, although I'll mention a few others.