PTC has announced the release of Mathcad Express. They
“Mathcad Express is a free version of Mathcad that allows any user to utilize some selected features of Mathcad Prime 2.0, for an unlimited time.”
“Mathcad Express does include the full capabilities of Mathcad Prime 2.0 for 30 days, for free. After the 30 day period has ended, you may continue to use the limited functionality of Mathcad Express as long as you like — the Mathcad Express license will never expire.”
You can see the difference between Mathcad Prime 2.0 and Mathcad Express in the table on the download page.