The service integrates seamlessly into my workflow: When I'm online on my laptop (well technically, when I'm online with Gtalk), then Olark shows the "Chat with the CEO" tab pictures above. When I'm not online, Olark automatically shows a "Leave the CEO a Message" dialog. When someone pings me through the website, it shows up as an IM from a Gtalk user named "Olark visitor".
I originally didn't know if I'd get too much spam or intrusive, non value-add pings by putting this on our company website. But I felt that it was worth the risk since a really high-touch user experience is key to the way that we do SDK marketing. And it's turned out to be a really great way for me to stay close to our userbase of mobile developers.
Just today I had a chat with a prospective SDK user that was pretty incredulous that s/he was actually chatting with the CEO. Below is a summary of the chat (every chat is emailed to me for archival after it concludes):