Ann and I have been using Avocado for the past few months to stay in touch while we're apart. It's been working well for us, but it didn't have a great workflow for sharing links (beyond copy-and-paste). Since it now has an API, I thought I could perhaps fix this with a Chrome extension.
About the only clever thing that the extension does is that if you're currently in a Google Reader tab, it will pick up the currently selected item's link to share. It relies on Reader exposing a
message listener and then has the
postMessage (since the main world can invoke the isolated world's event handlers). This is described in more detail in the extensions documentation.
For the sake of full disclosure, lest you think my graphics skills have suddenly improved, Avocado co-founders Jenna and Chris are friends of mine and they spruced up Cilantro's UI to look less