Aegis Industrial Softwares CircuitCAM can import a gerber file, and allow you to establish a pick and place program from it. It can also take a scanned image of the actual board to do this. It's a moderately painful process; but it is doable.
CircuitCAM also takes in CAD ASCII files, to help with creating a pick and place program. The ASCII input method is much easier and faster than the gerber input method. Most CAD files can output an ASCII file with all of the data you need.
I receive no incentives from CircuitCAM, though I am a happy customer.
Also take a look at vplan from Mentor graphics(Valor) this has very powerful CAD/CAM to centroid capability...can generate Centroid data from Gerber - creates packages , polarities and assigns Refdes with easy to use tool...
I can second the Unisoft Pronto software. We were in the same boat where getting centroid data files to program our AOI system was killing us. The Pronto software takes gerber files and BOMs and marries them into usable centroid data files for AOI programming. It takes me all of 5 minutes to create the files and has been a Godsend for us.
The rep we worked with as incredibly helpful. He's a little laid-back and every time I called him it sounded like I woke him up from a nap, but he was always available, day or night, and even weekends to help answer questions and get us up and running quickly.
We designed a fairly simple software called PROCAM to do exactly that! It takes 2 Gerber layers - Paste/Mask layer and the Silk layer. Within minutes you can extract all the centroids. PROCAM has a standard excel output with all the centroids, fiducial location and size, step and repeat etc. It can also perform CAD and BOM matching if BOM is available. We have also built Yamaha/Philips VIOS output format, Ipulse .csv format and GenCAD .cad and .pnl output.
We designed this software for one of our very good customer and are now selling it to others as well. It is a very low priced tool.