A handful of factlets about the next version of Windows and some URLs for further info for those interested...
1. Windows 7 is not Windows NT 7.0
This may sound confusing, but "Windows 7" is the product/project name for this generation of Windows.
Quick recap for product names & NT versions:
Winodws NT 3.1
Windows NT 3.5/3.51
Windows NT 4.0
Windows 2000 = NT 5.0
Windows XP = NT 5.1 (workstation only)
Windows Server 2003 / Windows XP Professional x64 Edition = NT 5.2
Windows Vista / Windows Server 2008 = NT 6.0
Windows 7 / Windows Server 2008 R2 = NT 6.1
(If each "generation" incorporates a Workstation and a Server version, then Windows 7 is the 7th generation.)
2. Windows 7 will be available in 32-bit and 64-bit flavours
Windows Server 2008 R2, however, will only be released as 64-bit
Windows Server 2008 R2: Scalability and Reliability:
Windows Server 2008 R2 is the first Windows operating system to be offered for only 64-bit processors. With customers being unable to purchase a 32-bit server CPU for over two years, the performance and reliability advantages to moving to this architecture were too beneficial to ignore.
3. Windows Virtual PC can be downloaded for Professional, Ultimate and Enterprise editions
"Windows XP Mode" is a pre-built (XP SP3) virtual machine requiring no licence and runs either as a regular VM or seamless apps on the Windows 7 desktop
- only 32-bit VMs are supported, but works identically on 32-bit and 64-bit Windows 7 hosts
- requires hardware virtualization support from the CPU & BIOS
4. No in-box mail client
Vista shipped with "Windows Mail", but Windows 7 will not have a mail client present by default (Windows Live Mail can still be installed for free as a download)
5. Release date for Windows 7 announced as 22nd October 2009
Today during a keynote address at Computex 2009 in Taipei, Microsoft’s OEM Division Corporate Vice President Steve Guggenheimer revealed that the company is confident with the progress made with Windows 7 and Windows Server 2008 R2, and that as a result, Microsoft will deliver Release to Manufacturing (RTM) code to partners in the second half of July. Windows 7 will become generally available on Oct. 22, 2009, and Windows Server 2008 R2 will be broadly available at the same time.
References:
MSDN: Combining Platform Extensions with Operating System Versions
Engineering Windows 7 Blog
What's New In Windows 7
Channel 9 Video: Mark Russinovich Inside Windows 7
Windows Virtual PC
Windows 7 and Windows Server 2008 R2 Timelines Shared at Computex
Edits:
2009-06-03 updated to include recently accounced release schedule