I would like to use the API to obtain the list of Programs which a Lead is a member. Is there a function that provides this information? There is a function for Lists.
This function is not available. The only way that I have been able to discern the information is by looping through the Activity Logs for a Lead and checking for a "Change Status in Progression" activiy
Unless you download all leads by program ID's for all programs and reverse the result, (Get Multiple Leads by Program Id » Marketo Developers ), which is probably what you do not want to do, this is not an info you can get from the API.
That would be an interesting API call to have, though. If you enter the idea, I'll vote.