Yale has capitulated to Peru's demands that artifacts from Machu Picchu be repatriated. See
The nastiness of Peru's concerted campaign against the University, which recently included staged demonstrations and even threats of criminal prosecution, belies the conciliatory language in Yale's press release. See http://culturalpropertylaw.wordpress.com/2010/11/08/peru-mounts-campaign-against-yale-to-reclaim-artifacts/
Presumably, this decision will just encourage other repatriation demands. It certainly underscores the fact that a pre-1970 provenance is not the "safe harbor" archaeologists have claimed in order to induce museums to change their acquisition policies.