This article pre-dates Mashup Sites 4 Sharepoint, http://www.jackbe.com/products/mashup_sites_for_sharepoint.php , which has been available as a product Add On since Presto 3. Mashlets have been replaced with "Apps". Having said that, since Presto 3, the equivalent to :
http://hostname:port/mashlets/standalone.jsp?mashlet=MashletName
is
http://hostname:port/prestohub/applauncher.html?mid=MashletName
also, uwa-view.jsp, which used in the iframe source url, is still bundled but it has also moved to prestohub context:
http://hostname:port/prestohub/uwa-view.jsp
so you need to update that too.


With Presto 3.1, what is the correct url for the TitleUrl property in a WebPart object?
In the code example (Using Custom Web Parts to publish Mashlets), the property returns:
http://hostname:port/mashlets/standalone.jsp?mashlet=MashletName
This url is not correct; there is no "mashlets" directory under the Tomcat webapps directory, and standalone.jsp does not exist in my Presto installation.