Hmm, well it's certainly worth consideration, but I'm not sure its the worth the time/cost. My LBS copied the serial number to the receipt for warrante use anyway, I would think most would (?) so it should not be too much more effort to periodically upload the info. To be worth it, though, you need a police force willing to be proactive in fighting bicycle theft. Will they make more than token responses to stolen bike reports? Will they commit to checking every last bike found against the serial number database? Will they look at programs such as decoy bikes, to catch thieves?

To be blunt I think any type of crime is only as common as it is convenient - if bike thieves, or vandals, or car thieves, etc. get get away with it, they will. If it is known that there is no active policing of an area, and/or that the crime will not be taken seriously, then you can expect a high rate of that type of crime. A bike serial number database could be a good tool if local police forces have the time, resources, and willingness to use that tool as part of an active crime fighting program.

As Al mentioned in this thread, I am also not willing to carve or stamp a number into a new bike - if for no other reason than it makes the bike unreturnable and would void the warrante on the frame. The bike has a good and unique number stamped into it already!