Is it possible to sync Salesforce activity tasks and events into Marketo? I'm not seeing any Marketo Nation communication on this issue.
SFDC Sync: Activity Sync - Marketo Docs - Product Documentation - Activity is logged/activity was logged is talked about in this link.
As Jackie mentions, you can view Tasks and Events as Activities in Marketo, but be aware that there is a limitation where only the standard fields on that object (Subject, Description, Assigned to, Date, etc.) are viewable or filterable--any custom field additions are not exposed, unlike other Salesforce standard objects.