For the 2010, i spent a bit of my time on poking with malicious PDF analysis. I came up with a technical write up for the analyzing malicious pdf. The title for the write up is "Getting Owned by Malicious PDF". I split the write up into multiple samples sorting from easy-to-moderate of challenges and obstacle when dealing with malicious pdf analysis.
The second sample involves with compressed PDF components by utilizing PDF feature, /Filter. /Filter will allow any PDF objects to be compressed using compression algorithms and decoding method such as zlib compression for /FlatDecode filter, ascii-to-hex for /ASCIIHexDecode filter. There are many methods can be implemented. Please read a good PDF Specification format by Adobe.
For the details on samples 3, 4 please feel free to download and read the write up from SANS's web page here.