Further information on how Xilinx System Generator and other HDL code generation tools may be used with MATLAB and Simulink -- including examples, demos, and videos -- are available from http://www.mathworks.com/fpga.
There are some very useful concepts covered here and the summary is generally spot on, however it is important to consider the DSP function in the system context.
If other functions are required in addition to the DSP it may push the solution of choice into an FPGA. For example, a low performance DSP function that is part of a sensor or motor control system need not be implemented in a stand alone DSP device. An FPGA might be the right solution in this case.
Another piece, originating from the first quarter edition 2012 of the Xcell Journal, is "Embedded Vision: FPGAs’ Next Notable Technology Opportunity".
To access the article, click here: http://www.eetimes.com/design/military-aerospace-design/4376567/Embedded-vision--FPGAs--next-technology-opportunity