Ted Molczan has identified the object as being likely DSCS 3-11 (00001A / 26052), last seen 178 days ago at another position.
UPDATE 14 Dec 2010: the object is PAN (09-047A), see here for the story of how this identification unfolded. PAN started to drift on Dec 1st.
This evening (December 8), while imaging PAN (09-047A) in a race against the clock with incoming clouds, I inadvertently imaged a UNID (unidentified object).
The object showed up in the images taken with the 2.8/180mm Carl Zeiss Sonnar. It is located about 0.5 degrees West of the commercial geostationary duo Turksat 2A and Turksat 3A. So far, I cannot find a match for it with any known (classified or unclassified) object. Below are the two images, taken 20 seconds apart:
It is either a geostationary object, or an object in Gestationary Transfer Orbit close to its apogee.
It got clouded shortly after this image series, so after discovering the object on the imagery I had no opportunity to go out and make additional images for more positions.
The two positions gathered are (in IOD format):
99999 10 342A 4353 G 20101208210402300 17 75 0513341-072580 56
99999 10 342A 4353 G 20101208210422300 17 75 0513542-072590 56