There was lots of promise -- Email is an ancient technology, and is due for a refresh. Google Wave promised to change the way we communicate, and would eventually replace Email. Unfortunately, Google decided to pull the plug on the project before it accomplished that goal.
So what should be learned from Google Wave? I think there are lots of great lessons that we can take away from the closure:
1) Just because you're a Google project, it doesn't mean you are guaranteed success Just because Google has massive reach, it doesn't mean that products they release immediate hits. Google often releases products that don't go anywhere -- most of the time they realize that, and relatively quickly pull the plug.
In reality, there are only a handful of services that Google has really nailed: Google Search, Gmail, Google Voice, Google Analytics, Google Chrome, Android and Google Maps are good examples. The Google graveyard includes services like Lively, Google Answers, Google Phone Store, and many more.
2) Buzz around a product doesn't equal success Google wave had serious buzz throughout it's life at points -- but that didn't translate into die-hard users. The same invite-only structure that made Gmail a success didn't have much of an effect on Google Wave -- those who did find an invite often had bad first impressions -- it was buggy, and was harder to use than Gmail.
I had seen several times on Twitter when Google Wave was trending -- lots of people knew about the service, and had accounts, but nobody loved it enough to stick with it. Users have short attention spans.
3) If it works, don't assume people want to fix it Email works great -- really, it does. Everybody knows how to use it, and it's easy to explain to someone that doesn't. Google Wave was a tool that could technically be used for so many different purposes that it is impossible to explain. If you can't explain it in a short sentence, it's too complicated for the people that would make the product a success.
People know Email, and don't see any reason to swap it out for something different. It's a mistake to assume otherwise.
Google's intentions with Wave were great, unfortunately, it was a really tough sell. Who knows, if someone picks up the open source project and runs with it, perhaps it can still be a game changer, but I'm thinking it will go down the same path as Jaiku -- another one of Google's abandoned projects.