Is it possible to use the data from the form in the URL of the thank you page?

This used to work but now appears to no longer work.  Was something changed? 

Is this option still available?

I'd like my thank you page call to be something like:

http://mysite.com/thankyou.aspx?fname=firstname&lname=lastname

This is still possible and accomplished in the same manner as before, but the layout of the wizard has changed. You can see how to achieve that by following the steps in this guide: Redirecting Users to a Different Page

Do just note that the link above is OK, but that you would need to change the fields slightly.

For example if "firstname" and "lastname" are values that are sent from the form, you need to change it up to:

http://mysite.com/thankyou.aspx?fname={firstname}&lname={lastname}

This guide would be of help as well: Prepopulating fields to your JotForm via URL parameters