From Automator workflows broken in 10.6 :
Automator action workflows are now
called "Services". If you want your
plugins or workflows to work again,
do this......
Here's an example:
If your Finder plug-in workflow
doesn’t work,
In SnowLeopard, services provide a
powerful method of adding
functionality to the Finder and other
applications. Services supersede
Finder plug-in workflows. If you use
Finder plug-in workflows created on an
earlier system, you must manually turn
them into services.
To create a service from a Finder
plug-in workflow:
Open the old Finder plug-in workflow.
Choose File > New.
Select the Services template and click
Choose.
Choose the type of data your service
requires as input in the “Service
receives selected” pop-up menu, and
then choose an application from the
“in” pop-up menu.
If the service should be available in
all applications, choose “any
application.”
If you want the service to behave
exactly the way the previous Finder
plug-in workflow did, choose “Files
and folders” from the “Service
receives selected” popup-menu, and
choose "Finder" from the “in” pop-up
menu.
If you want selected text overwritten
with text modified in the workflow,
select the “Replaces selected text”
checkbox.
Click the Finder plug-in workflow
window to bring it to the front.
To copy all the actions in the
workflow, choose Edit > Select All,
and then choose Edit > Copy.
Click the new service workflow window
to bring it to the front.
Choose Edit > Paste.
Here is another detailed description of the process, with screenshots :
Updating Finder Workflows in SnowLeopard.
For some more examples see :
3 Easy-To-Create Simple Automator Workflows For Everyday Use.