No, this is not possible at all in the client. Once a user has access to a
project within project pro they have access to the entire project data same
as in 2003.
In PWA you can limit visibility to certain columns and possibly to rows of
data by creating specific views with only the columns you want to show and
adding filters to hide specific tasks you don't want to show (which would
require some custom tagging of those tasks) in the Project Details views.
In 2007 the filter that you define in the view cannot be modified or even
seen by the end user using that view, this is new in 2007. You could then
use the category/group/view security functionality to make certain views
hidden or visible to different users.
Jonathan
