IAALBTINLA (I am a lawyer but this is *not* legal advice)
1. The original write owns the copyright to the code.
2. By posting it to the BB, he might have agreed to license it under whatever terms by which the board operates. This might mean you have some license to use it (either implied or actual).
3. The code copied by the developer might not be enough of the work as a whole to considered infringement.
4. One test for determining whether computer code infringes copyright, in the USA at least, is the classic, yet ambiguous "abstraction, filtration, comparison" test. (If the copying was complete with comments, then that's not so good for the copier, but if the code accomplishes a trivial function, then not so much.)
5. Speaking generally, it's important to be on the lookout for situations like this. For instance, if code is copied from an open-source project, then significant consequences can follow (c.f. the Asus story below this one.)
6. If you are concerned, talk with your company's legal counsel.