Yes, the original SC, as well as Warcraft 2+3, and a mix of other (mostly turn-based) strategy games.
Do you think that the original SC helps as much? You have to do a lot of "clickfesting" in SC1, which you're spared from doing in SC2. Which means much more thinking in SC2. Wow.
I've run across a couple of questions about the value of dual n-back, and this is the best place I know of to find people who've worked with it.
If you've tried it, has it noticeably improved your working memory? Was it enough to be worth the time?