The commercial skip is available the next day, and only on the small, well-defined set that is primetime network shows, so I assume Dish simply analyzes the show and sends the commercial start/end frame #'s down to the STBs. So we have yet another case of "illegal numbers" like the DeCSS episode.
What would be interesting is if the STBs were flexible enough to allow peer-to-peer download of commercial frame #'s. Then bored IT nerds could be posting commercial times 30 seconds after a show ended. What would the networks do about that?
Personally I use Windows Media Center and comskip, so all my commercials are skipped automatically, but this is not a regular-Joe type of solution.
In a truly free market, commercial marking would be allowed, but then the networks would simply:
A. switch the advertising to be "in show" with crawls, pop-in graphics in the corners, etc.
or
B. pay per episode with only short ads like Hulu does ("This episode of CSI is brought to you by Acme Metal Detectors")