Finally the vSphere Client is supported on Windows 7 & Windows Server 2008 R2:
Windows 7 and Windows 2008 R2 support — This release adds support for 32-bit and 64-bit versions of Windows 7 as well as 64-bit Windows 2008 R2 as guest operating system platforms. In addition, the vSphere Client is now supported and can be installed on a Windows 7 platform.
You can find the downloads and release notes here:
ESX 4.0 Update 1: http://downloads.vmware.com/d/details/esx40u1/ZHcqYmQlcGpiZGVqdA==
ESXi 4.0 Update 1: http://downloads.vmware.com/d/details/esxi40u1/ZHcqYmQlcGhiZGVqdA==
vCenter 4.0 Update 1: http://downloads.vmware.com/d/details/vc40u1/ZHcqYmQlcCpiZGVqdA==
vSphere PowerCLI 4.0 Update 1: http://downloads.vmware.com/d/details/sdkwin40u1/ZHcqYmQlcHRiZGVqdA