In this case, using the conjunction "and" or not using it is NOT merely a "question of style" -- in fact, it gives the sentence quite a different meaning.

With the "and", it would generally be understood that the "SETICon 2 conference" and the "panel discussion" are two separate events at which Filippenko appeared -- possibly even taking place in different locations and different years:

Filippenko spoke at the SETICon 2 Conference in Los Angeles in November 2011, and during a panel discussion about the Big Bang in New York in March 2012.
Without the "and" (as you quoted it from MSNBC), it's understood that the "panel discussion" was a specific part of the larger "SETICon 2" event. Furthermore, it's implied that Filippenko only spoke in the "Big Bang" panel discussion, but not at other discussions or meetings that took place during the SETICon 2 conference.

If Filippenko spoke at various events during SETICon, but you want to particularly emphasize that he took part in the Big Bang panel, then you could say something like:

Filippenko spoke at the SETICon conference, most notably during a panel discussion called "Did the Big Bang Require a Divine Spark?"
OR you could say:

Filippenko spoke at the opening ceremony of the SETICon conference, and during a panel discussion called "Did the Big Bang Require a Divine Spark?"
This second example is different from the MSNBC quote because you're mentioning two separate events that were on the program during the course of the larger event, both of which Filippenko spoke at. (But the MSNBC quote, as I said, implies that he spoke only in the panel discussion.)