The OSD chip that we use is the STV5730A. ST had tried to stop making this part, but demand was too great, so they simply increased the price. It puts out NTSC/PAL.
A lot of OSD chips don't, most are for monitors, so if you want to go to a TV you would have to add an NTSC encoder.

Philips has stopped making a lot of the more interesting 8051/OSD combinations that it used to make.

Mitsubishi also makes a number usable OSD chip, we've used the M35062. It's more difficult to buy (Mitsubishi doesn't really seem interested in selling them unless you want to buy 10K parts; we got ours through AllAmerican distributor) and the datasheet is pathetic, much worse than ST's. The part works pretty nice in spite of its datasheet.

Dennis