Sometimes you can really feel stuck between a rock and a hard place with IE6 - it's a lousy, insecure sack of crap, yet there's a significant number of people still using it.
Personally, I take the view that until the Internet becomes unusable on IE6, people (and lazy IT departments!) won't upgrade. So it's definitely time to forget about it and just put in a conditional css statement that hides the website and displays a nice little paragraph suggesting that perhaps it's time to upgrade. Heck, even some links to some proper browsers. There's nothing to stop people from continuing on to the website (with the lengthy IE6 compatibility hacks if need be - it's important to remember who your clients are) but at least they've been educated.
The longer support is kept, the longer it'll have to be supported.