Mahara Version 1.5 allows you to embed <iframes> in Mahara.
The installation comes with a number of standard sites pre-set up eg YouTube, Glogster, Slideshare.
This excellent page on the Mahara wiki has been set up by Dirk (who teachers Maths, Science and Computing) and lists a number of addition iframe sources that you (as an administrator) can add to your Mahara list.
He welcomes further contributions
See on wiki.mahara.org