We have an implementation of llRegionSayTo in OpenSimulator now. This is similar to llRegionSay, in that an object may send a message over a channel to other objects anywhere in the region. But with llRegionSayTo, you are able to address individual objects by their uuid. If the uuid is an avatar, then the message will be delivered in chat on channel 0. And the message will also be sent to all attachments on the avatar.
This is a pretty handy command that can find use in things like combat systems, region-wide accessories that need individual central updates, etc..