Support for MailChimp Groups?

In MailChimp, besides the fields you can add to a mail list, MailChimp has Groups to let you assign a list member to one or more groups, so you can send messages to part of the list.
When configuring my Gravity Form, however, I haven't yet figured out if its possible to assign someone to one or more MailChimp Groups based on answers given in the Gravity Form.
Here's my scenario...
I have one list at Mail Chimp.
Everyone who completes the Gravity Form is assigned to the All Members group, but only those who say Yes to a Newsletter choice in Gravity Forms are also assigned to a Newsletter group.
Is there a way to populate the Group field in a MailChimp list?

Having multiple MailChimp lists isn't good because you end up with duplicate people in the lists. And what happens when a user needs to change from one group to another? Much easier to have one list and assign each member to a MailChimp Group.

For now, a work-around is to embed a hidden field in the Gravity Form and write that into a MailChimp field. By having several forms, each feeding a different user group and a different hidden field value, you have one MailChimp list with different user groups identified.

But it would be best to have Gravity Forms support the Group concept in MailChimp.