We´re currently testing the MindPlan Mac beta in the Snow Leopard operating system that came out on 28th of August 2009.
In short, Snow Leopard is not currently supported by the MindPlan 3.1 Standalone beta for the Mac, because there are a few issues that we need to fix first.

The issues that we have discovered so far:
Issues in JFileChooser:
The "Open MindPlan" dialog is not working due to changes in the internal structure of the Java Virtual Machine. We were using JVM version 1.5 so far, but Snow Leopard forces applications to use 1.6. It does not contain 1.5 at all, just links from "1.5" directories to the "1.6" directories. Our code referenced classes from 1.5 that have changed in 1.6, which is breaking the dialog functionality.

NullPointerException in license manager dialog:
The license manager throws an exception when you click on a license row entry with the left mouse button.

Issues with Application window in Expose:
Sometimes the application window is not displayed in the OS X Expose view. Instead, there is a hidden window "mindmap.notes.MindplanControlFrame". This window is only used in the Windows OS (the Mac version uses the same code) and did not show up in Mac OS X Leopard.

Current status:
There may be other issues. Tests have just begun yesterday right after the OS upgrade.
The first two issues are already fixed, the Expose issue is being worked on. It looks like it will not take long until the beta version is working properly again.

I will publish a new MindPlan 3.1 Mac beta build in the MindPlan forum as soon as it is available. I will also start an internal discussion to officially release and support the standalone Mac version. That´s really overdue, but we were working on a different code stream in the last months. More on this in a later posting in the MindPlan blog.

Regarding the MindPlan Composite Application version for the Mac:
IBM development has notified us that issues that we had with the MindPlan CA version in Notes 8.5 (keyboard shortcuts not working) have been addressed in the latest Design Partner Code Drop of Lotus Notes 8.5.1.
We still need to verify this.
Those issues were a showstopper for a MindPlan CA release on Notes 8.5, so hopefully we can release the CA version as soon as 8.5.1 is out.