Though I wasn't able to watch it live (until just before the end of the game), the DVR did record the 7 and 8 pm CDT airings (in addition to the 4pm airing earlier in the day), and there appears to be some inconsistancy in exactly what and how it was broadcast.
The 4pm broadcast appeared to be (and was indicated in the program info as) a repeat, but without checking the recordings from last summer, the first segment (up to commercial break 1) didnt seem to connect with the rest of the show (the "Arial Tweato Special Edition", I'll call it), as it featured the first married couple in Wipeout (which I don't remember from before), and there was a reference to "those glasses" which probably was not mentioned in the original airing. Then, at what should have been halftime, the 7pm airing started (late for the start of the live coverage, it seems) in SD, had some audio problems, and eventually switched to HD for the remainder of that segment, up to the commercial break. Then, after the break, the show continued (a repeat) in SD. The 9pm slot started with another repeat airing in SD, then at approx. 9:16, there was a fade, and the live "Wipeout Bowl I" started (in HD only).
So, if you were trying to watch/record "Wipeout Bowl I" and HD only, you were probably very hard pressed to figure out what was new, what was a repeat, and what was MEANT to be HD (at least for Comcast Chicago).