Google just turned on email notifications in Wave. That's great news if you've gotten your hands on an invite but haven't kept up with the going-ons inside—easy to do when you're not in the habit of visiting the site.
Using notifications is pretty simple stuff (click the drop-down next to your Inbox to see the dialog pictured above), and the implementation seems smart:
From the Notifications menu, you can select the frequency of your email updates. If you are an infrequent Google Wave user we would recommend the “immediately” setting, but you can change it at any time.
When you’re added to a new wave, or a wave that you are on changes, we’ll send you an email with a short summary of the text and links to go straight to your updated waves. Rest assured, we know waves can change a lot, so we will only send you one notification about a changed wave until you have logged in to look at it (i.e.: if a wave changes 10 times after we send the first notification, we won’t send 10 more emails). Waves you have open also won’t trigger updates.
Maybe you won’t need to run a completely separate Wave notifier to keep up with Wave after all.