One solution is to style the left border like so:
li { display: inline; }
li + li {
border-left: 1px solid;
margin-left:.5em;
padding-left:.5em;
}
However, this may not give you desirable results if the entire lists wraps, like it does in your example. I.e. it would give something like:
foo | bar | baz
| bob | bill
| judy