If implementing a design hacked for IE6 is limiting your abilities as a designer, especially if there are time constraint issues, the better alternative is campaigning IE6 users to upgrade, and only implementing the graceful degrading bits you have the time for. After all something less than graceful is now called for, beings that IE6's failure to comply with many web standard features has long been known.
If on the other hand a client is cognizant of the compromises you as a designer are faced with, and is willing to lessen the impact of the design and user interface, by sacrificing certain features for all site visitors, then maybe that is the better route than providing any progressive enhancement at all.
What it boils down to is you don't fail a design idea, because IE6 just can't make the layout work, or that the hacks would take so long and still may not be workable and you just don't have the man hours to attempt a solution for IE6.
Internet Explorer 6 message that can be seen on http://youlove.us if you are unfortunate enough to be running IE6
-- or -- if you have IE6 on your machine and want to load it just for kicks.
The folks at YouLove.us have done a pretty good job here of preserving the content that they could for IE6, the point being cutting-edge websites call for at least leading-edge browsers.
Friendly Warning Text:
Unfortunately, due to the restrictions of such an old browser (Internet Explorer 6 is now almost 7 years old!) you won't be experiencing the full goodness of this web site.
We strongly recommend upgrading your browser to a modern equivalent such as Internet Explorer 7, Firefox 2 or Safari 3, not just because you're missing out on some great design possiblities, but also due to the fact that Internet Explorer 6 is rather a security hole.
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SaveTheDevelopers.org (STD)
http://www.techcrunch.com/2008/03/25/save-the-developers-stop-using-internet-explorer-6/