The website zol.com.cn has a listing for a Pentax K-3 DLSR camera with a 24MP APS-C sensor. No other details/specs were provided. According to Ricehigh, this Chinese website has a good track record and has correctly predicted specifications of other upcoming cameras in the past. Rumors about a full frame Pentax DSLR has been circulating for a while, but it seems that the camera will not be announced at Photokina.
The K-3 and X-5 cameras plus the DA 560mm f/5.6 lens are probably going to be the only Pentax announcements for Photokina. Few months ago there were some rumors about a new medium format camera, but I have not heard any updates recently. The Pentax K-01 is also rumored to be replaced soon (but not for Photokina).