More info here
http://www.uspto.gov/web/offices/pac/doc/general/faq.htm
Wikipedia
Patent pending
Main article: Patent pending
Patent pending is a term used to describe an alleged invention that is the subject of a patent application. The term may be used to mark products containing the invention to draw competitor's attention to the fact that they may be infringing a patent if the product is copied after the patent is granted. The rules relating to the use of the term to mark products vary between patent offices, as do the benefits of such marking. In general, it is permissible to apply the term patent pending to a product if there is, in fact, a patent pending for any invention implemented in the product.