Why shouldn't she? This is 2011, not 1957. Women are liberated: they have power, more opportunities, careers, positions of influence, sexual freedom. Why shouldn't they go after what they want in life, including romance? Why should they have to sit by the phone and wait to be asked out?
I always say that life is short and you should go after what you want with a vengeance. You've no doubt heard the expression carpe diem, or seize the day. The same applies to romance: seize the guy (carpe dude-em). If you're interested, hell yes, ask him out. Most guys love it. We get tired of having to be the aggressor and risk-taker all the time, so we're thrilled when a woman shows interest in us first.
Be aware, however, that some guys are hopelessly old-fashioned and might be turned off by a confident, proactive woman. That's a chance that I think is worth taking. If a guy is that prehistoric/sexist, you probably don't want to date him anyway.
Thanks for the question.