If you are discussing features, making comparisons, talking about game theory, etc, then you can mention other games. Even a casual reference in an otherwise on-topic post would be ok, as long as you don't start asking for help in other games, or something (which should be done in the chat or RPG chat forums, depending on the type of game).
D2:ED doesn't need a lot of hype, but people are not going to buy it if they don't know about it. With a couple other RPGs being released late in the year, we should at least see references or comparisons in various reviews.
