A couple recent cases have addressed several key issues with prosecution bars. As you know, it has become common for protective orders in litigation to include provisions that prohibit a person from receiving certain highly proprietary information if that person engages in "competitive decision-making," which can include patent prosecution.
In Unwired Planet LLC v. Apple Inc., 2013 WL 1501489 (D. Nev. Apr. 11, 2013), Apple persuaded the district court to expand the bar to prevent outside counsel who had access to certain Apple confidential information from giving advice on "patent acquisitions." The district court found that there was a risk that Unwired would determine which patents to buy to target Apple products.
The other issue that is percolating has two aspects to it: do existing prosecution bars cover IPR and, if not, should they? The first issue turns on the language of the existing protective order. The second on whether IPR permits the same sort of risk of patent prosecution. These issues were litigated in Politec Inc. v. Scentair Tech., Inc., 2013 WL 2138193 (E.D. Wis. May 17, 2013), which reached an odd balance. It held that IPR was within the scope of the bar, but allowed outside counsel to participate but prohibiting them from amending, substituting, or adding claims during IPR.
If you have an existing protective order, these cases counsel to examine whether it is broad enough, either for IPR or for other activities.