Last week I did a MOSS development training AND a one day feature-overview seminar at Microsoft, apart from the fact it was a busy week I got the same question in both appearances:
'Is it possible to extract a workflow created with the Sharepoint Designer from a site and deploy it as a feature?'
The answer, as far as I can tell is 'No'. Patrick has posted a blogpost about how you need to position Workflow Foundation against the Sharepoint platform. Very good (and not to elaborate so it will take you only a minute of your time) material. Read it here