It seems to me that using Google's Wave removes tempo/spatio constraints. That means it realizes REALLY-realtime collaboration.
Though, as far as i know, Screen Sharing function by Skype and Apple's iChat has already changed our way of collaboration over spatial constraint, Google's Wave lets us share everything including archives of past's communication in realtime.
What is a wave?
- A wave is equal parts conversation and document. People can communicate and work together with richly formatted text, photos, videos, maps, and more.
- A wave is shared. Any participant can reply anywhere in the message, edit the content and add participants at any point in the process. Then playback lets anyone rewind the wave to see who said what and when.
- A wave is live. With live transmission as you type, participants on a wave can have faster conversations, see edits and interact with extensions in real-time.
source: "About Google Wave" by Google Wave
What is Google Wave (Japanese)