If memory serves me, Yukon was delayed a while back, with a target date of late '04. SQL Server magazine generally praised the decision, not only in recognizing the abundance of caution from MS, but also because so many organizations were just getting their feet wet going from SQL Server 7 to SQL Server 2000.
Given the history, I never expected Whidbey in '04 anyway. There's so much they're trying to accomplish with respect to the CLR (and Longhorn), and they only have one real chance to get it right. And then there's the 'S' word (security)...
So while Whidbey looks tremendous and should be easier to migrate to than the first .NET release, it gives many of us a longer timeframe to further understand those aspects of .NET that likely won't change in Whidbey.
Kevin