17 Days
For those of you who actually come to my site from time to time, you'll have undoubtedly noticed my little counter in the right corner of the sidebar. What that tracks is how long my website has been active in the corner of my living room. If you're on a paid hosting account, fire me off an email whenever your server goes down so I can keep track against how mine's doing. So far I'm at 17 days straight without any downtime.
If you check out Media Temple's status blog, you can see that they've had 50 minutes of outage during the last three days. Based on their own blog entries, they are running at 99.7% uptime (although based on the outages I experienced and their duration, I think it's actually worse than that).