I had missed that entry on Matthew Thomas's weblog:

So how should you mark up text in another language? Here's what I used in my original example:

<i lang="fr">je ne sais quoi</i>

Instead, Matt May suggests

<span lang="fr">je ne sais quoi</span>

and, in his style sheet, italicizes any span with a lang attribute using a simple attribute selector.

These two options have exactly the same semantics. The only difference is that Mr May's version doesn't work in Internet Explorer for Windows. Or in Internet Explorer for Mac. Or in Opera in User Mode. Or in Mozilla with Basic Page Style selected. Or in Firefox with Basic Theme selected. Or in Lynx.

That's a bit of a difference, I must say :-) Very well said, Matthew, very well said.