Posted by Andrew.
Adam Ostrow posted an article - "Coming Soon: Google Chrome Extensions", he noticed a Google developer conference scheduled for May 27th will include a session on developing extensions for Chrome.
There is a list of sessions at Goolge I/O, you will find a session “Developing Extensions For Google Chrome”:
Sessions at Google I/O
May 27 - 28, 2009 Moscone Center, San Francisco
Google I/O offers 80+ sessions that present highly technical content on Android, Chrome, App Engine, Google Web Toolkit, AJAX and many more. A subset of the content is currently available, providing you with a preview of what I/O has to offer. We'll be updating this session list so check back frequently
Developing extensions for Google Chrome
Learn how Google Chrome makes it easy to write extensions using the web technologies you already know. This talk will cover the basics of the extension system (distribution/packaging, installation, updates), as well as the different APIs to enhance with the browser.
Google has published the extensions design documents for developers.