When land is sold WITH objects, subsequently to the sale llGetOwner called from scripts in child prims of those objects continues to report the previous owner. If the new owner takes and then re-rezzes the object the problem rectifies itself. However, this could be problematic for complex builds, e.g. houses with scripted doors/windows that rely on checking ownership for some secure operations (this was my experience with a system that uses object ownership as a means of elminating potential cross-chat between similar systems owned by different avatars).
This issue appear only to affect the child prims of objects sold with land. Root prim scripts report the correct new owner immediately after sale. Neither does it affect objects sold as objects with "original" or "copy" sale modes.
A possible workaround which I have not tried is to use llGetOwnerKey( llGetLinkKey( LINK_ROOT ) ) from the child prim, but in general scripters will expect llGetOwner to return the correct owner in all circumstances.
The issue is easily reproduced by using a two-prim object, each prim having a script that reports the owner on touch. Place said object on a land parcel and then sell the land WITH objects to another avatar. Then touch each prim. The root will report the new owner, the child prim the previous owner.