I'm the social media manager at VR and came across this thread. You can absolutely populate your newsletter with content from your blog and link your readers back to whatever domain, post, or object you choose. We have many customers that are wordpress users (both .com and .org) and use our app to send out newsletters with much success. All emails are created and sent from our dashboard when you log in to your account at verticalresponse.com so you don't have to worry about any specific WP plugins.
The widget that timethief linked you to is just a plugin for adding a newsletter signup form to your wordpress site and they are correct that it will only work on .org sites, though I believe there are some workarounds for .com users who want to do this too.
Your best bet would be to contact our support team if you need specific questions about the app's functionality. The various contact options for them can be found here: http://www.verticalresponse.com/support
Hope that helps!