Some cheap camera manufacturers have added to the confusion. Some label their web cams "HD" as a marketing term and not necessarily a technical fact. Since 1.3MP webcams are standard 640x480 VGA, you really need to move up to a 2 MegaPixel webcam or higher to achieve the minimal 720 pixels vertical resolution true HD video requires.
The ultra-high 720p and beyond sensor technology has gotten somewhat ahead of the technology curve. Many video chat and capture programs have long been entrenched in the world of lower resolution image standards. The classic 3:4 screen aspect ratio at 320x240 and 640x480 VGA resolution have been long-held video conferencing standards that delivered acceptable frame-rates. Most home internet connections are barely fast enough to do 720p video, 1080p is simply too much data for a home cable or satellite internet connection to provide
To really take full advantage of HD web camera 720p and 1080p resolutions, you need both a fast dual core CPU computer and a very fast internet connection. You also need applications that are "HD Aware". It takes high-speed internet bandwidth in BOTH directions to pump all the pixels HD images require for a good chat experience.
Video conferencing programs need to be specifically written to sense and detect 720p and 1080p webcam capabilities and their wide-screen aspect ratios. The bundled applications that come with the HD webcam| web camera make this trivial issue for Windows users. However, Macintosh users may find an OSX compatible Mac HD webcam support rather limited in available resolution choices depending on which Mac OS video programs they use.
We recommend buy a HD web camera now for the latest generation of technical improvements in image clarity and detail, lighting sensitivity and niticably improved color response - while we wait for the other pieces of the rather intensive computer system and data bandwidth requirements to match up with the demands of true HD video conferencing.