Advertising on Twitter now supports Gender Targeting

Twitter has enabled gender specific targeting. As Twitter’s advertising product blog states, they are using secondary signals to guess gender rather than use an explicitly stated Gender data field, which as you may have noticed is not asked by Twitter. Twitter estimate they get it right around 90% of the time, and where they cannot establish gender, they will not offer that user profile to advertisers.

More details here: http://advertising.twitter.com/2012/10/gender-targeting-for-promoted-products.html