This sort of came up in this thread the other day. I haven't heard anything abotu the "a" revision to HDMI. Going to be interesting to start seeing hardware with v1.3 running.

Q. What is the difference between HDMI 1.3 and HDMI 1.3a, or 1.3b?

For consumers, there is no difference between HDMI version 1.3 and 1.3a or 1.3b. These minor revisions to the specification typically relate to manufacturing or testing issues and do not impact features or functionality. In addition, HDMI Licensing, LLC is actively working with manufacturers to reduce confusion for consumers by de-emphasizing version numbers and focusing instead on product features and functionality.

For Adopters, the latest HDMI Specification is v1.3a and the latest HDMI Compliance Test Specification (CTS) is 1.3b1.