The following code code works in Digital Editions as well as Firefox and Opera (but not Safari).
Code:
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<body>
<p>Here is inline SVG:</p>
<svg xmlns="http://www.w3.org/2000/svg" width="100" height="100">
<g xml:space="preserve" font-size="10" font-family="monospace">
<rect x="0" y="0" width="100" height="100" fill="none" stroke="blue"/>
<text x="30" y="20"> XXX </text>
<text x="30" y="30">X X</text>
<text x="30" y="40">X X</text>
<text x="30" y="50">X X</text>
<text x="30" y="60"> XXXX</text>
<text x="30" y="70"> X</text>
<text x="30" y="80"> X</text>
<text x="30" y="90"> XXX </text>
</g>
</svg>
<p>A paragraph after SVG</p>
</body>
</html>
g tag is strictly speaking not needed, all of the properties could go to svg. Unfortunatel it does not work properly in DE. (It works for standalone SVG, but when SVG is embedded in XHTML, svg tag is somewhat in between two worlds and it gets confused).