CampaignMonitor.com has run some extensive tests to find out which CSS3 properties can be used when designing newsletters. I have been playing around with CSS3 lately and as many other web designers, I'm sure, just can't wait until there is better implementation of these new standards. I have already tried designing with just code and using Chrome, but always have to head back to Photoshop to finish off details in buttons or headers. Soon enough, I hope to be able drop Adobe's expensive software from my list of essential applications as a web designer. In the meantime, check out Campaign Monitor's list of which CSS3 properties work in which email clients or their example of an email campaign by Panic using many of these features.