For this download link http://s3.amazonaws.com/dist.springs...1.3.0.CI-1.zip
I got this error:

<Error>
<Code>AccessDenied</Code>
<Message>Access Denied</Message>
<RequestId>F805F0BD710BDB2F</RequestId>
<HostId>
vs2ebhYQUVSAd2sxS7/ezYXSgfWOGq1wrU2mqXJqyfaxrM30Ikx3nN9ZTdVtc33+
</HostId>
</Error>

You find that link on the se-workflow homepage:
http://www.springsource.org/extensions/se-workflow

Kind regards