Microsoft already has a Windows 7 Beta Customer Preview Program on their MSDN site where they encourage us to: "Evaluate and jump-start your development efforts on Windows 7 Beta".
Do you feel it is worthwhile to spend my time now re Windows 7, or should I wait a few releases, or even until after Windows 7 is released?
What are the advantages and disadvantages to starting this early?
I've downloaded the Windows 7 beta and will be installing it into a VM shortly.
There's really no reason not to check your stuff on it now. It's way better for you to find and fix any problems before your users do.
I've installed windows 7 on two computer. So far, there has only been one small issue (the software did not find a USB device). I ran the compatibility wizard and now it works fine.
They have made it easy enough for a end user to take care of.
It's basically Vista 6.2. Lots of good improvements but not a new operating system. So it's no rush to test,
As Paul said, there's absolutely no reason not to start now. What you fix now is something less to fix later - and you also get the benefit of having an application that is deployable on an OS that over 2.5m people are expected to download and install over the next few weeks.
Of course, you can expect to run the risk of having to make minor adjustments to your program as bug fixes are implement, or as new features are rolled out, but what you do now will still save you time - even if it just saves you having to become familiar with any platform-specific constraints further down the line, when pressures from potential clients, customers, etc. will be significantly higher.