Sadly it seems Google Wave days are limited. Google is pulling the plug on their Wave service sometime after the end of this year. I was surprised to hear that Wave was not doing too well, I have used it nearly every day since I got private beta access to the service. There has never been a tool created on the web that could allow true real time collaboration and also auto documents the collaboration. Video conferencing can not hold a stick to Wave, video does not provide any useful record of the conversation or a way to pick it back up immediately from where you left off.
There are probably several reasons why Wave failed, however I believe the biggest is that Wave never hit its tipping point. The saddest moment with Wave is right after you first launch it, when you realize none of your friends are their. Wave is nearly completely useless without others to use it with. I got lucky because I work closely with several people across the United States, we saw Wave as the perfect tool to help us work together. I can imagine a lot of users are not so lucky and just couldn't find a use for Wave in their personal life. To combat this, Google should have integrated Wave directly into GMail. A user should have not been able to tell the difference between a Wave and an Email, except that in a Wave the other user could see you typing your message.
Wave really could replace about 80% of my emails, mainly the ones that are for debugging or brain storming. Their will always be emails that a Wave could not replace, like receipt from Amazon purchases. Wave would revolutionize digital conversations within businesses. In order for that to happen however, Google would need to make a push for other services to be able to host their own Waves, like the current state of Email. Where I can send an email to anyone, even people outside of Google. Wave should have been explained as Email v2, and Google should have pushed it that way.
I'll be sad to see Wave disappear, hopefully Google has a good plan to bring the benefits of Wave back.