Yesterday Oren announced the release of RhinoMocks 3.5.  While the RC version has been out for a bit the RTM release fixes a few bugs.  You can read all about the enhancements and features in Oren's post. 

The feature that excites me the most about the new RhinoMocks release is the AAA Syntax (Arrange-Act-Assert).  One thing I've always struggled with when explaining mocking to people is the record replay model.  The new syntax seems to be more natural.  I have no empirical evidence to back that last statement up, only anecdotal evidence from observing fellow employees interact with the new syntax.

A close second in terms of changes is the deprecations of CreateMock().  In all the features, patches, improvements, and bug fixes this is the only item Oren bolded, which shows it's importance:

CreateMock() is deprecated and marked with the [Obsolete] attribute. Use StrictMock() instead.

This one is great for beginners who instinctively pick up the binaries and see the method CreateMock() and end up later with brittle tests.  Brad Abrams talks about the "Pit of Success" and quotes Rico Mariani:

The Pit of Success: in stark contrast to a summit, a peak, or a journey across a desert to find victory through many trials and surprises, we want our customers to simply fall into winning practices by using our platform and frameworks. To the extent that we make it easy to get into trouble we fail.

In earlier versions of Rhino it was too easy to use CreateMock() when DynamicMock() is what you wanted.  New mockers were often using the wrong method (I was one of these CreateMock() abusers/users).  The warning when using CreateMock, and the other enhancements/changes, make falling into the pit of success (with mocking) a much more likely reality.

You can download the bits from Oren's download area.  When you download, I would encourage you to make a donation to Oren's open source efforts.