Detect if two vectors are on the same parcel?

I want to find out when I've moved off a particular plot of land; so assuming I have vector a = llGetPos(); then the object moves around some and I do vector b = llGetPos(); is there any way to determine if a and b are on the same plot of land? llGetLandOwnerAt() isn't sufficient since you have large strips of public owned land that are broken up in to multiple parcels, or one person might own several adjacent parcels all with different settings.

No parcel-level land ownership detection yet, sorry.

If you know the boundaries of the land, easy. If you don't, nothing automated.

If you are the owner of the land, you can check for overmyland. That's about it.

Eddy tho I'm not sure why you want to do this. You might find llScriptDanger() useful. This function detects if the land at pos has outside sctripts/building turned off.
It could help determine if the parcel is different from pos to pos, or just use to avoid non-script land.