It's worth noting, though, that when they say "working on WoW," they don't mean developing the Crusaders' Coliseum or even Outland -- they're talking about the original design of World of Warcraft for the release way back in 2004. Even though Blizzard didn't announce the next StarCraft until a few years ago in 2007, production actually started seriously (with multiplayer first, strangely enough) right after the launch of WoW, in 2005. Which makes the choice all the more intriguing: they decided to delay the RTS even before they knew WoW would be the runaway success that it is today.
Guess the choice paid off. The beta of StarCraft II should be kicking off any day now (you all got keys at last year's BlizzCon, remember?), so even though that year delay was caused by WoW way back at launch, we'll see if they've had the time since to make a game that'll meet players' expectations.