Title says it all. I'm not the hugest Apple fan but this is a sad day.
Apple.com has a tribute up on the front page.
Even though I'm not a huge Apple fan, I did have a Titanium Power Book in grad school (G4 at 1Ghz in a notebook! Incredible for 2002!) I have a lot of fond memories about that thing, including having a Unix prompts with SSH sessions all over campus open over a beautiful GUI. Steve Jobs was always able to express himself through Apple's products. You might not always like his expression, but you could tell that he really did care very much about what Apple's products were all about.