I'm pushing to adopt quickly, and positioning projects to take advantage of the new features. Some projects I'm saying "Well, we could do it now but could we wait 6 months?". Of course I think I'm the exception to the rule.
From the masses out there I think it'll be mixed adoption. They'll be a small group that are forerunners and jump on it. They'll be a middle of the road group that will probably be the 6 month to 1 year wait and see type. Then they'll be some that are still struggling with 2007 (and some with 2003) that won't upgrade at all until the next version is out there on the horizon.
I think the important thing for adoption is upgrade capabilities. It's never fun to upgrade. 2003 to 2007 was painful and very few tool vendors have produced the best toolsets to take care of this. Microsoft needs to consider legacy systems (I'm calling 2007 legacy now). If they truly want adoption and tout that SharePoint is the collaboration space they need to be serious about dealing with peoples data and provide a path. Just putting out the latest and greatest but then having to wait for vendors to fill the gap to get your data from 2007 to 2010 isn't going to cut it. It's a tough battle but one that needs to be fought.
In the interim, get the public beta when it comes out and get it into your lab environment. Bring in a subset of your data from production and see what mock upgrade scenarios are going to be like. The recent change to stsadm.exe to check your farm for any issues to move to 2010 is a good step so be sure to run that and keep your farms running smoothly.
When you evaluate what can be done with 2010 and align it to business processes to get the biggest bang for the buck take the dive. Always drive your solutions from the buisness need though and there are going to be gaps in the solution space so watch for third party vendors and free CodePlex-like projects to fill those gaps.
Above all, have fun. The 2010 system is the same kind of major upgrade that 2003->2007 was and offers a lot of great new features (and some fixed ones) that everyone can benefit from.