News about Windows Installer 4.1 and 4.5

Microsoft is working on two new versions of Windows Installer (MSI):

Windows Installer 4.1
MSI 4.1 will be available in Windows Vista SP1 and Windows Server 2008. According to the Windows Installer SDK this version will not add any new features. Windows Server 2008 is currently in beta and expected to be released later this year.

Windows Installer 4.5
One of the goals in Windows Installer 4.5 is to improve installs that consist of multiple msi packages, thus enabling products to be split into more granular msi files. For this purpose it adds APIs that a chainer can call to install products in a multi-package transaction. So there will be Install and Rollback transactions across multiple msi files. The chainer itself will probably not be part of MSI 4.5 Instead Microsoft asked MSI tools vendors to support these new features in their products.

MSI 4.5 will also address servicing issues where uninstalling a patch could break if a component is shared across multiple products.

The MSI 4.5 redistributables will be available for Windows XP SP2 and above and will include the operating system independent features and fixes from MSI 4.0 which is only available on Windows Vista.

Beta registration for MSI 4.5 opened a few days ago, you can apply at the Microsoft Connect site, where Microsoft manages beta programs. The beta documentation should be posted there in July and the binaries in August.

See Windows Installer Team Blog