No, for many reasons. We don't want to stop certain players playing on our servers simply because their internet is not good enough, restricting it to only people with good connection.
As well as that, ghosting players can't hit you... and usually can be hit.
It would also be very difficult to code, as the servers would have to send packets to every player in order to gauge the ping, so we don't want to waste time coding a not very useful feature when there are more important features to implement.
I understand the first point clearly.
As to the second point, it's hard to hit ghosting players when they're teleporting all over the place. The closest thing I get to a "hit" are the sparks, although they don't take damage.
Finally, the third point. Why do you have the reinvent the wheel? Just take an existing plugin and put it on the server, or in the SurvivalGames plugin? Decompile.
http://dev.bukkit.org/server-mods/alreadyping/
It's license allows you to decompile it and use it freely (GPLv2).
I suppose the lag would be an issue as well, but since they already reduced the amount of lobby lag that you get when you log in I don't see it as an issue?
I'm going to drop this suggestion now, seeing as the first point you've mentioned outweighs the others.
