Copyright in an idea or an expression?

Kim Weatherall, abandoning her self-imposed exile, has a close look at recent Federal Court decisions finding that one project home builder's plans had been infringed by others who adopted the alfresco feature ... 

Kim here; Metricon v Barrett Property Group [2008] FCAFC 46 and Barrett Property Group v Carlisle [2008] FCA 375.

For obvious reasons, I shall refrain from comment.