Data Integrator has a nice documentation generator which is available from the Management Console. The generator can create documentation that contains textual descriptions and graphical representations of local/global variables, work flows, data flows, and other objects as well as their relationships - even database table usage. I would love to see a similar built-in feature in SSIS. I supposed for the time-being we have to rely on 3rd-party tools or building custom code to parse the XML in .dtsx.
Auto Documentation provides users the ability to select the repository and job available. The documentation can be printed as either PDF or Word doc. The level of detail allowed is impressive. As I've found out it can be overwhelming if all of the options is selected for a moderately complex job - 100+ pages for a job with 70 some objects.