When I tried to edit a SharePoint List in a datasheet view a received the following error:

The list cannot be displaued in DataSheet view for one or more of the following reasons:

- A datasheet component compatible with Windows SharePoint Services is not installed.
- Your Web browser does not support ActiveX controles
- Support for ActiveX controles is disabled

I tried it with a SharePoint 2010 and a SharePoint 2007 List, both returned the same error.
As I had office 2010 on my machine. It seems that you have to install the 2007 Office System Driver: Data Connectivity Components for this to work.