Fourier Transforms and deconvolution? No need to go "No Way Out" on the image yet guys 😉
The tool to use to attempt this in Photoshop is "Unsharpen Mask" or "Smart Sharpen" (for CS2). Use repeatedly with moderate settings (70%, 1px, 1 level). Another trick is to reduce the size then sharpen again. How well either of these techniques work depends on how blurry the original is and what the intended use of the final image is. The lower resolution your final version will be (eg used on a web page vs 8x10 print) also increases your chances of success. Sometimes the image is just too blurry but trying the above might help. Good luck.