Which 'contact information' format has the broadest support for mobile phone QR code scanners?

Question

vCard? mecard? hCard?

Is there a de facto standard at this point? I've never personally owned a 'smartphone' -- is there a format that's supported 'out-of-the-box' for either iphone, android or blackberry?

edit:

• found this discussion from last year. Any thoughts?

  • this reader appears to be multiplatform and uses mecard

  • mecard spec