Which Macs support HDCP on their built-in / native displays? Which Macs, both desktop and portable, support HDCP on their native displays? The web is awash with information on connected displays, and which support it, don't support it, and stories of people who weren't warned that theirs don't support it, paid $15 for a movie, and are now screwed.

But for internal displays, I can find nothing. Apple's own Technical Specifications do not list HDCP support. Everymac.com has nothing. I was once able to play an HD iTunes movie on my Late 2008 MacBook Pro, but had to take a leap of faith that it supported HDCP. A StackOverflow answer indicates even a motivated developer couldn't make an app that determines whether a given Mac has HDCP support for its built-in display.

It seems the only way - not exaggerating here - is to buy some protected content from iTunes and hope it works.
Basically every modern mac with an embedded screen supports HDCP.

iTunes will play all copy protected HD content on all integrated displays (MacBooks and iMacs) but not on non HDCP displays.

This lets us deduct that the integrated displays are HDCP compliant or at least that Mac OS ignores the DHCP flag when playing protected HD content on the integrated screen.

Apparently you might get this strange error, which leads me to think that Mac OS simply bypasses the HDCP check when using integrated displays.