Yes, I've been very confused by this. "About me" appears under Marketo > Admin > Field Management, under "SFDC Lead Field" on the right.
This was what made me expect to see the data in SFDC. It's a "SFDC Lead Field", right? "About me" doesn't appear in our Salesforce instance at Setup > App setup > Customize > Leads > Fields, so I'm left wondering what the point is.
I think I will use "Person notes" as that seems to sync to salesforce as "Description" - thanks, Amber.
Does anyone know, did we create "About me", or is it something that came with Marketo?