Please note that .NET 4.5 is an in-place update to .NET 4.0. Therefore, all the WF 4 samples mentioned below work on the 4.5 runtime.

WF 4.5 Samples

WF 4.0 Samples

You can download the official WF 4.0 Samples from here.

These WF Samples have been categorized as following:
Here are a few more samples in addition to the official WF 4 samples:

Rules Samples