It's unclear what cars will and will-not be included at this point, but our assumption is, since the issue relates to possibly roadable cars being properly titled, it may impact concept and one-off specialty cars rather than important-production-run vehicles. Here's the statement from BJ:
We are very pleased to offer a group of specialty cars from GM during the Palm Beach Auction. However, we have been told there are some issues related to the sale of some of the vehicles, and that GM will be unable to resolve these issues in time to include them in the 2009 Palm Beach auction. This information was communicated to Barrett-Jackson at 4 pm EST on Thursday, April 9, 2009.
Barrett-Jackson regrets any inconvenience this may have caused to any of our customers. As always, our primary concern is protecting the best interests of the bidders, consignors and spectators of our auction events. We will provide additional information as it becomes available.
UPDATE: It turns out the auction will include all the cars as every issue has been resolved According to BJ:
"The Acting Administrator of NHTSA, Ron Medford, has communicated to Barrett-Jackson that previous issues concerning the sales of the GM Collection have been resolved and all sales can go forward."