The best way was to signup for developer sandbox. I don't know if its too late for signing up for sandbox account, but here is the link https://services.google.com/fb/forms/wavesignupfordev/. Everyone using sandbox has access to google wave beta preview. Beside, sandbox account will allow you to create bug and notify developer team which makes you valuable in times if they release a new product. I have my sandbox account since July 2009. I am surprised that none of you have heard about it before or tried it.