BriefMobile has some interesting information regarding the Samsung Galaxy S. First, it appears that the American varieties of the GS can output High Definition video via a special Micro-USB-to-HDMI cable. This is a specially engineered cable that will be available only via Samsung (at least initially).
Secondly, BriefMobile reports that a leaked Froyo-based ROM has been released by Samsung Firmwares for the Galaxy S. This is not for the American versions (Vibrant, Captivate, etc.), only for the Galaxy S i9000. It is an official Samsung release, although it appears to be a developer’s build. So, if you’ve got an i9000, attempt at your own risk.