I know of at least three incidents. The CouchDB talk at a Ruby conference in 2009 had soft porn pictures [1]. Another Ruby conference in 2008 offered a 'daycare' where attendees could leave their 'spouse, boyfriend or girlfriend' if they weren't interested in the conference itself. They called it a 'girlfriend daycare' which generated some controversy on a mailing list named DevChix. [2] These aren't the most objective and reliable sources, its just to give you an idea of that drama.

Also BritRuby was cancelled because the speaker list consisted entirely of white males, which is somehow a bad thing. [3]

[1] http://geekfeminism.wikia.com/wiki/CouchDB_talk

[2] http://geekfeminism.wikia.com/wiki/RubyFringe_offers_girlfri...

[3] http://venturebeat.com/2012/11/18/britruby-conference-felled...

A Ruby conference was cancelled:

https://gist.github.com/seanhandley/4106776

And for more drama:

http://rubydramas.com

EDIT: more facts

There was a presentation relating CouchDB and "Performance" in a sexual way some years ago.

One of the first RailsConfs (perhaps even the first one) had male/female drama... There was a chatroom somewhere that people were on while the presentations were going on and some folks said some questionable things and a woman blogged about it.

I ended up having to apologize to the woman :O

2009 http://gadgetopia.com/post/6794