I've started using Google Wave recently (thanks to a colleague of mine, James McQuarrie) and up-front, I'll say that I don't get it. I currently don't see the usefulness of it in my current situation (I'm working in a team that's all in the same room). However, I got an invite to the Google Technology Users Group (#gtug) talk on Wave by the Wave developers themselves so I thought I'd go along and see what all the fuss was about.
They started with a few videos of what the whole thing is about (the pulp fiction one is my favorite) and I was starting to understand that it's a very fancy collaboration client with lots of other features that are 'still to come'.
And that seemed to be the main theme of the talk: there's more to come. They were talking about draft mode, extension gallery (paid-for apps too), translation, spell check, more languages, better keyboard shortcut support, mobile web versions (iPhone native app NOT in the works) and open libraries. There's a lot there and they've got a lot of ideas which they "don't have the resources to do", and that's an interesting point.
Yes, it's really early in the days of Wave, a product which has been "workable" for 5 months now, but they can't push new features in until their core changes are complete. For this reason, Google haven't open-source'd the core functionality or built all their API hooks yet, so developers are having to hack around problems.
The Google IO video also mentioned that you'll be able to build your own Wave servers for private use. These servers will have to contact the main Google Wave servers, and all communications between these two will be cryptographically signed, which is major news. There's quite a large overhead of performing this and for larger organisations, they may have to shell out for dedicated hardware.
Steph and Lars (the presenters) also talked about e-mail integration. They said they had it working for quite a long time but didn't like the way that it interfered with other waves, so they dropped it. They're hoping that the community will build it for them.
They also mentioned that it's very popular in the USA, Canada, UK, then France and Brazil. China is half way down the list but Korea is nowhere to be seen. For a country that has the highest Internet connectivity per capita that seems very odd.
Finally they mentioned the Client API, and the lack of one. There's no intention of making one either as they want everyone to use the web interface.
In my opinion, there's so much more to come and I can see some very good potential uses (apparently lawyers love it). At the moment though, it's still very early days. There's so many basic things they've still got to work out, test and tweak, and then it'll be ready for the prime time. Still, will it beat e-mail? I'm not leaving Outlook behind just yet.
Disclaimer: I work for PA Consulting Group, but the opinions above are not those of PA and are entirely my own.