Later on, Newell is asked about the possibility of a direct crossover between Portal and Half-Life, as both games are set in the same continuity. Newell did not directly confirm such a crossover will take place, but he did say that setting both games in the same universe has a purpose.
"When you're thinking about games, you sort of want to think about how characters collide. In their current forms, Chell and Gordon are very similar characters. in terms of the phenomenology of their experiences. ... In terms of having these people coexist at same time and same place, that's ... part of the reason Portal and Half-Life are in the same universe."
Take it as however you like it.