The HDMI spec keeps evolving. Current spec is 1.4, which supports Ethernet, 3D, Deep Color, etc.
Basically, you need a cable that supports the capabilities of your device. If you have Blu-ray, a modern-ish HDTV (1080p), etc., you should probably get a v1.4 cable.
However, get it on Amazon.com. No need to pay the exorbitant prices at a Best Buy or similar (>$50). You can get a good cable online for $10.