Does anyone know how to find out if they are on the newest version of MSI? We're moving toward Salesforce Lightning and my CRM team needs to know if we are on the newest version of MSI. Given that we implemented MSI in Spring 2016, I'd assume not, but I'm not sure where to find that info.
The latest version is 1.4259.2.
When you click on the appexchange link from Market doc (https://appexchange.salesforce.com/listingDetail?listingId=a0N30000001SVZmEAO), and then on the "details" tab, you get that info on the right pane of the screen.
In your SFDC instance (setup-> Installed packages) you can check whether or not your version is up-to-date.
Upgrading is quite easy and straightforward : just install the latest version without deinstalling the previous one (Upgrade Marketo Sales Insight for Salesforce1 - Marketo Docs - Product Docs )