to respond I must make a terminological introduction. I will be brief and sometimes imprecise. Perhaps I have already spoken about it, but I don't remember in which discussion...
The human voice has two important "registers", chest and head. Registers are particular timbral qualities that can be used in certain parts of the vocal range. The chest is generally used for low notes, the head for high notes. In singing practice, the use of only chest or only head is almost always avoided, and this is the reason why we almost always sing in a register defined as mixed.
Now, traditionally "falsetto" is the technique that involves the almost exclusive use of the head register. It is called falsetto (in tradition) because it falsifies the voice, meaning it makes its typical characteristics less recognizable. This is also called "timbratura" [timbre-shifting/thinning] and is strictly linked to the elimination of other registers. By eliminating chest, mixed, and other resonances, in short, you eliminate the characteristics of YOUR voice, lightening it and making it "false".
This extreme case, which is the only one that should be called falsetto, is VERY RARE, because in reality all those who claim to sing in falsetto actually sing in mixed register. Stevie Wonder is an example; even in very high notes we are all able to perceive a rich "grain" of the voice, a homogeneity between the low and high notes. The most blatant example of a "more falsetto-like" falsetto is that of the singer from Cugini di Campagna
http://www.youtube.com/watch?v=6vr-EI05kB4 the entire first phrase can easily be sung in a very timbral mixed register, whereas he voluntarily thins the timbre to seek a very clear color. This leads him to have very clear, diaphanous, and thin-timbred high notes.
A contrary example can be the famous caballetta for tenor from Donizetti's La figlia del reggimento, the one with the do... http://www.youtube.com/watch?v=tgqpQKEXtYQ even though it is mixed, this is a very timbral mixed register. Timbre is fundamental in operatic singing, even in the techniques of so-called falsettists, i.e., male singers who sing in female registers or in castrato repertoire. This is a contralto friend of mine, who doesn't thin the timbre for even a single note http://www.youtube.com/watch?v=OMnFG2H2G1A . Look, to define this voice as falsetto, in the traditional sense, is absurd...
Coming to the problem of "falsetto in women". The problem is that it is very difficult to understand how much head and how much chest women use in high notes. The register transition is much more homogeneous by nature and the timbre is more complex to perceive. A small lesson on register changes is the piece "Amore lontanissimo" by Antonella Ruggiero
she uses nasal resonances a lot, although it seems that during that evening at Sanremo she had a fever, so she wasn't fully controlling the resonances... anyway, around minute 1.10 she says "mi farò ancor più piccola", and she sings it in a register close to falsetto (thinning the timbre and using a lot of nose); then at 1.30 she sings "amore lontAnissimo", and on the "a" she does the same note as before, but in full mixed register, with timbre (and the difference is very noticeable, even though she is still singing softly). At minute 2.55, then, there is the famous ascent into true falsetto "mi farò ancor più piccola", and this indeed is a sound very close to the female falsetto. Same thing at 3.40 where, in fact, she puts her hand to her forehead :-) if she really had a fever, as they said at the time, she must have felt it vibrating a lot in her head... if you have a cold or a fever, high notes in falsetto cause a lot of discomfort in the eye sockets :-)