Is there a built-in text-to-graphic utility for OS X Lion?
ImageMagick doesn't come with OS X, but it should though.

convert -background skyblue -border 10 -bordercolor skyblue -fill 'hsb(10%,50%,50%)' -font /Library/Fonts/Arial\ Narrow.ttf -pointsize 24 label:"some text" output.png

If you have to specify some more complex styles, using webkit2png might be easier.

echo "&lt;style&gt;em {padding:5px}&lt;/style&gt;&lt;em&gt;Test&lt;/em&gt;" &gt; test.html
webkit2png test.html --clipwidth=55 --clipheight=35 --scale 1 -C