This would be amazing! We're working in some new lead sources at the moment (ones where the lead doesn't necessarily visit the site), so Web Activity reports aren't cutting it anymore. This would help SO much!
You can accomplish this to some extent by creating a lead report (e.g. start with a 'Leads by Source' report). Add the custom columns option and select the smart list that you want to subscribe to. Then change the 'Group Leads By' setting to 'email address'. Then in the smart list, add 'Member of Smart List' and select the smart list that you want to subscribe to.
@Tole, I don't think that quite gets us what you think it does... This will only show you email addresses of those in a smart list, not all of the custom view / column options available in a standard Smart List. I know you said, "to some extent", but that is so limited as to not be useful. If I'm missing how this can give us extra information in the report beyond just the email (because that's what we've grouped by), I'd appreciate further guidance.
Hopefully this is next up on the Product Roadmap. 400+ likes and an open idea since 2010, this really should already be possible.
Anybody with Marketo Product Management able to provide a hint as to which Quarter we might see this delivered? If we won't see it until October or beyond, I will need to write some custom code for a current project... if we will see it beforehand, I can check a need off our list as 100% fulfilled by this feature.
Would love to know how close this is to becoming a reality...