<p>Semantically speaking, is there an appropriate place in today's websites (late 2008+) where using the bold <code>&lt;b&gt;</code> and italic <code>&lt;i&gt;</code> tags are more useful than the more widely used <code>&lt;strong&gt;</code> and <code>&lt;em&gt;</code> tags?</p>

Never. They are removed in XHTML 2.0 as they are presentational tags.  CSS should be used to bold/italicise content.
edit:
If you're looking for a purely presentational tag, that's what the
```
SPAN
```
tag with a class and a little CSS is for.