How can I show what page a form was submitted from?

Not really. Most of the time I put in the {{lead.Last Interesting Moment Desc}} which often does have that page or Form name. You have to ensure that your Interesting Moments are setup to trigger on certain pages or Forms.

You can post a hidden field with any form that includes the page's URL or friendly name, call it "Last Form Fillout Source" or whatever. Like @Josh said, no built-in token.

Thanks.  Very strange that this is not a built in feature.

Sanford - how would I capture the page's "friendly name" (I guess the Page Title)?

Thanks again!

<script>MktoForms2.loadForm("//app-ww01.marketo.com", "XXX-YYY-ZZZ", 999,
    function(form) 
    {
        form.setValues({ LastFormFilloutOnPage : document.querySelector('TITLE').innerHTML });
    });        
</script>

Thanks Sanford.  Clear that we need help from our consultant to implement this. It does seem that a company requires an in-house developer/coder to make the most of Marketo. Wish we had known this during the sales process!!

@Angela G I don't think you need an in-house developer -- I'm technically a consultant and usually only spend a handful of hours on production Marketo integration code per month (but many more hours on experimental code I can use later if the need arises).

But you would benefit from having a skilled JavaScript/Marketo developer who you can call as needed, and that dev needs her/himself to be diving into Marketo on the regular -- you can be a rockstar JS developer in general, way better than me, and still have no idea what's going on with Forms 2.0 until you get past the learning curve.  And no company wants to pay someone to learn from scratch, and then relearn if they haven't touched Marketo in months! (Unless, as you mention, they're on salary and it's understood.)  

Re: sales, Marketo has vastly expanded their APIs of late. I imagine they're caught between [1] advertising developer extensibility as a major feature and [2] skipping over it as it may cause concern for some clients.  Remember, if I hadn't chimed in to worry you, you'd still have @Josh's workaround! :)

Again, Sanford, thanks so much! That certainly makes a lot of sense, and I think as we explore and discover Marketo we will need to find the line between what we tackle in house and what we outsource to a specialist. It's certainly exciting to see the full scope of what is possible.

I am working to try and use both suggestions for this issue.

Thanks!