Among my friends, peers, and coworkers (generally 22-40), I've noticed many women calling mixed groups - and even groups of women - "guys". In the same groups, in casual parlance, women will call other women "dude".

I think these terms are losing their gender-specificity and merely becoming a way to refer to a generic (non-sex/gender specified) person.

Of course, depending on your peer groups, and the level of formality in communication, your situation may be different. (i.e. if your entire peer-group is hypersensitive, politically-correct language police, feel free to modify.)