Waveboard is described as 'was a client software for Google Wave for both Mac OS X 10.5+ and iPhone OS 3.0+'. There are three alternatives to Waveboard for Online / Web-based, SaaS, Android, Chrome OS and iPhone. The best alternative is Moo.do, which is free. Other great apps like Waveboard are Rizzoma (Free, Open Source) and kune (Free, Open Source).
Email and IM are linear contextless communication tools. Messages pile up and get lost or become redundant. There's no way to keep track of who replied to what, or which version of the conversation is the newest.