A little late, but I had the same problem.
Then I found the difference:
If I use an English language web site and create a workflow then I see the additional action in the SharePoint Designer, but If I use another website with another language I did not see the action items.
Solution: Open the template for English language (1033) directory on the Sharepoint server.
In my case: C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\1033.
In the sub directory "Workflow" you will find the file: CustomWorkflow.ACTIONS.
- Open this file in an editor. On the top you find the entry:
Change it to:
- Copy the file CustomWorkflow.ACTIONS in your language directory.
In my case it is German and the template directory 1031: C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\1031\
- I believe that your data are cached. IIS reset is useful ( I waited a night) and after this time I found the Actions also in my other Worflows (in other languages).