if you modify this slightly, and use it in this form it seems to work:

$a = "foo|{baz|qux}|fax";
@b = ($a =~ /(
        [^|\{]+
       |
        \{ [^}]+ \}
        )
        (?: \| | $ )
      /xg);
[download]

@b now contains:

$VAR1 = [
          'foo',
          '{baz|qux}',
          'fax'
        ];
[download]

Note that this regexp can't cope with recursive brackets, and can therefore be fooled. Any example of this would be:
$a = "foo|{baz|{qu}x|fax";
which would result in:

$VAR1 = [
          'foo',
          'baz',
          'qu}x}',
          'fax'
        ];
[download]

I'm afraid that I haven't got round to getting the owl book yet, so i'm not really that hot with regexps yet. In fact, i'm coming back to perl now from a years absence. If someone could show how to modify the regexp to cope with things like this, I would be grateful.

Yoda