So much of SharePoint is built on XML/XSLT.
It's time I updated my skill set from just a few years ago when I hacked together a "web-scraper" out of Perl. The output file was pure XML with the proper headers to make an RSS feed. The scraper worked for a week, until the regular expressions it looked for changed. Soon the company's RSS feed was being created manually by simply editing the XML file and adding a new node.
With SharePoint, you need not worry about creating properly formatted XML. The application spits out XML as easily as a hobo spits out teeth. The real factor here is what you can do with the XML as presented, and that's where the XSLT comes in. XML is a breeze, but XSLT files take some skill.
The Data Form Web Part contains an <Xsl> tag wherein transforms are done.
What is it transforming? A data source.
Where is the data source defined? In the .NET code, directly above the <Xsl> tag.
What's .NET code? Ask me in 6 months...
You're lying? Like a rug...
My life was once filled with fancy server-side scripts, but now I'm just another SharePoint consultant.