Microsoft has released Windows 7 to manufacturing, indicating that it will start appearing in OEM computer systems in the near future. Typically, it takes 4-6 weeks for a Windows release to be manufactured, reach the system manufacturers, find its way onto new systems, and have those systems sold to users. That means that end users should be seeing Windows 7 offered by the likes of Dell and HP sometime in early to mid September.
You have to wonder how many enterprises have been staying with Windows XP rather than upgrade to Vista over the last several years. I've seen few organizations move en mass to Vista, and those that have seem loathe to admit it. While there seems to be an up swell of interest in staying with XP (if it's not broke, don't fix it), look for a fairly fast migration to Microsoft's latest.
Developers, for better or worse, aren't going to see much new in Windows 7, at least not much that was already in Vista. Microsoft has not dropped Windows Presentation Foundation (WPF), so developers still need to understand the details of this new presentation layer, employing XAML and the Expression suite in order to build new user interfaces. While WinForms is still supported, as Microsoft moves further into the WPF realm, it is clear that the new technology will be the dominant approach to building applications in the future.
At the same time, Microsoft also released Windows Server 2008 R2 to manufacturing. While not so much of interest to developers, it is certain to give IT administrators some consternation, requiring that the new release be thoroughly tested prior to deployment. Developers will likely also have to pay attention to any new features or changes from the server side in order to make sure server-based code continues to work correctly.