Yes and no:
Yes the rule of thumb is equally valid for computer screens as for TV screens.
No your daughter won't become a raging lunatic from watching you code.
The recommendation against watching TV is not, as I understand it, because it shortens the attention span, but because it overloads the mind. A small child is not mentally capable of processing so much visual input and will be overwhelmed. Especially if the child is sitting too close to a big screen.
If your child is far enough away that the screen is not a major visual object, and you're not flicking between apps that are visually wildly different (Outlook, MS Word, Firefox, Eclipse -- they all look the same from the other side of the room), then I see no harm coming from the monitor itself.
Baby mobiles are popular with infants because their slow visual changes are pleasing. I'm not saying your monitor is pleasing in the same way (but a screensaver probably would be!), but it does explain why she stares at it so much. Also, whatever engrosses you is bound to stir your child's attention too. Kids don't want to play with the parents' smartphones because they're smartphones but because the parents constantly play with them - so they must be intriguing.