I already explained in earlier post how to publish SharePoint sites through UAG (from 2007 to 2010 and Extranet/Internet site).
However, there was still an issue with SharePoint blog published through UAG (but this can be applied to any SharePoint site which have RSS Feeds enabled).
Indeed, RSS feeds were not successfully managed by UAG and so were not published.
To allow RSS Feeds to pass through UAG (as other SharePoint content done), open your UAG truck where your SharePoint blog is published.
Click on the Configure button to manage advanced configuration for the trunk.
Go to the Portal tab and click on the Edit button for ‘Do not parse the response bodies to these requests’
On the top list, locate your SharePoint blog application and then click the Add button for the URL’s list
Enter the following ./_layouts/listfeed.aspx.*
Repeat this step for any other SharePoint application with RSS Feed enabled.
And activate the configuration.
Et voilà, your RSS Feed is allowed through UAG.