Actually, I think I presented that wrong, and what I was thinking of can apply to the first one too. What I meant is that you can be referring to right now, or you can be referring to later in the day, depending on context. It's just because "today" is such a large frame of reference. Yes, "now" works too, though using it by itself typically implies that it's a changed state (if you don't want to imply that she was busy before, you would usually use "right now" or "at the moment").
If you omit "today" in any of these examples, by the way, "right now" is generally implied, unless some prior context causes another particular time to be implied.
Sorry for being confusing.