Dear jsjc,
'right.reports.product.viewed' in the standard layout, but it depends on your design theme.
If you look into the layout (in this case app/design/frontend/base/default/report.xml), the you will see anything as:
<default>
<!-- Mage_Reports -->
<reference name="right">
<block type="reports/product_viewed" before="right.permanent.callout" name="right.reports.product.viewed" template="reports/product_viewed.phtml" />
<block type="reports/product_compared" before="right.permanent.callout" name="right.reports.product.compared" template="reports/product_compared.phtml" />
</reference>
</default>
You have to put the content of attribute 'name' into field 'Layout names of dynamic loaded blocks:' on the tab 'Dynamic loaded blocks' in the M-Turbo administration.
If you are not familiar with Magento design developing contact your developer. He tell you where is defined block 'recently products viewed'.