Please review lastest status of oracle db and Mac OS
Oracle Database on Unix AIX,HP-UX,Linux,Mac OS X,Solaris,Tru64 Unix Operating Systems Installation and Configuration Requirements Quick Reference (8.0.5 to 11.2) [ID 169706.1]
The latest Oracle Database release for Mac OS X is 184.108.40.206 ( 11gR2 ) . Its a client-only release and certified on Lion and Mountain Lion ( 10.8.2 ) . You can download the instant -client zip files from OTN.
Yes it can be installed on directly on the hardware ( non-virtualized ) environment ) , if that's what you mean .