As announced on the community site, Windows Workflow Foundation (WF) Beta 2.2 is available here.

A very important point to note: You can not install this on top of an installation of the February CTP of WinFx.  So, if you have WinFx installed you will have to uninstall it, all the pieces and parts, in order to install Beta 2.2. If you are focused on a solution that only leverages WF, and not WCF or WPF, and want to upgrade to a newer version of the bits which are closer to the version which will be released, this is the path for you.  If you are building a solution that leverages additional WinFx technologies, you will want to stick with the February CTP. 

The install of Beta 2.2 contains all of the components (see below) of a WF install, and is titled the "Microsoft Visual Studio 2005 Extensions for Windows Workflow Foundation Beta 2.2."  That's a mouthful.  For Beta 2.2, this is the only thing that you need to install.  A summary of the changes are contained here.

On to a completely different topic.  I've also gotten some questions about why the WinFx install contains what seems like 3 different installs.  The simple answer is that there are really three components to WinFx (and thus, applies to WF).

• The WinFx runtime:  This is all you need if you want to run WinFx applications.
• The Windows SDK: As WinFx is a platform component of Windows, it has a Windows SDK component, consisting of samples, documentation, etc.  This is what you need if you want to build WinFx applications. 
• The Visual Studio Extensions:  This is the design component that integrates with Visual Studio and contains documentation to that effect.  This is what you need if you want to design WinFx applications in Visual Studio.  A similar component is the CTP of the "Orcas" designer for WPF applications (available here).

So, three pieces: runtime, SDK, designer, and now you know why they are there.