There is now an update of this tool for CRM 2011: (http://crm2011sharestep.codeplex.com)
A simple custom workflow activity to share any record that can be shared or remove sharing to any record in CRM 4.0.
CRM 4.0 provides workflow steps to create, update, assign records, but not to share/unshare them. This custom workflow step will do just that.
You can share a record with up to two teams and two users in one swoop. You can also remove all the shares before applying new ones.
It's not rocket science, but it's useful, at least for me.
To use this assembly, copy it into the C:\Program Files\Microsoft Dynamics CRM Server\Server\bin\assembly directory (or wherever your server base directory is) and use the Plugin Registration Tool (http://code.msdn.microsoft.com/crmplugin) to register it. Now
you will have one extra step to chose from while creating workflows: Utilities -> Share Record. Click on Properties to set the input parameters.