Internet Explorer 6 (IE6) will be 8 years old in August. That's ANCIENT in the technology world. Yet many web designers still find themselves supporting IE6. Should you? For the UCLA Gateway (http://www.ucla.edu) in July 2009, 62% of our visitors were using IE and of that 35% were using IE6.
The Digg Blog (http://blog.digg.com/?p=878) talks about the issues they faced. One of the main reasons people are still using IE6 is that they have no other choice. Their departments, organizations, work, etc. have strict control over what gets installed on their computers. According to Digg, "Three out of four IE6 users on Digg said they can’t upgrade due to some technical or workplace reason." As a result, many are locked into IE6.
Whether you decide to support IE6 is up to you. I would suggest looking at your stats to see what percentage of users to your site are still using IE6. For the UCLA Gateway, 35% is still a big number and we will continue to support it. There's a great article entitled "Definitive Guide to Taming the IE6 Beast" that helps comprehensively explain various methods in which you can support IE6.