Thanks to Koldo Madariaga, I have just discovered that you can add an embeddable Google Wave right on your website. And just like Koldo, I love embeddable objects :-)
As Google explain you can "add the Wave Element to your site so visitors can see and interact with the wave on your site. This is an easy way to take advantage of the collaborative power of Google Wave".
To get started, just find (or create) a wave you'd like to embed and then paste the link into the "embeddable Google Wave" box. Waves are only viewable by participants on the wave but you can make a public wave by adding email@example.com