In the spirit of common sense Blizzard are to finally introduce an ‘Appear Offline’ mode.
The “Appear Offline” status option will be added to World of Warcraft, StarCraft II, and Diablo III separately in future updates for each game. For Diablo III, we expect to add the feature in a patch after 1.0.5. For World of Warcraft and StarCraft II, we expect to add the option sometime after the release of each game’s upcoming expansion.
Thanks for your continued feedback, and we’ll share more information on the availability of this new feature in the months ahead.
Unfortunately, it’s rather a half measure as if you set yourself to ‘Offline’ you will appear so to all friends, you can not select which ones see you as such (if you were trying to hide from certain folk, not that any of you lovely people would do such a thing).
Thanks to Muriel for the heads up.