Penelope Stowe of the Ubuntu Accessibility Team told me about Blogging Against Disablism Day. Disablism and ableism have the same meaning and are more regional than anything else. They refer to the underlying assumptions about what "everyone" can do. I live not far from Gallaudet University, the only accredited liberal arts university for the Deaf and Hard of Hearing, so I actually come across people signing with some frequency.
When I first started signing, the friend who was teaching me (whom I met through the LoCo even!) would simcomm, and I learned from that. Now she usually doesn't speak at all when I'm around. She can safely assume I'll get enough context clues to learn whatever signs she uses that I didn't already know. I'm really happy about having achieved that level of fluency.
Last year, I used simcomm to give my presentation at Ohio LinuxFest. Mel Chua (Red Hat) and Bryen Yunashko (openSUSE) were both there. One is Hard of Hearing; the other is Deaf. I used a lot of ASL that weekend, not just for my own communication, but also as an interpreter for those giving directions. A few other hearing people even came up to me and started signing, since they saw me signing with Mel.
Maybe some day I'll be a certified interpreter. Right now, I can interpret in a pinch, but it's not pretty and doesn't have very good grammar. The trouble with simcomming so much is I have very little practice with using ASL-word-order. I intend to take an actual class to try to fix that.
I'm happy to see OLF has welcomed requests for assistance from disabled* attendees and speakers. I suspect I don't see many Hard of Hearing or Deaf people at conferences because they can usually safely assume there will be no accommodations, meanwhile there are no accommodations because organisers can usually safely assume there will be no HoH/Deaf people.
I don't know much about technological accessibility for those with hearing impairments. I do know Mel has complained that she has no way of knowing her system bell is on until her coworkers get upset at how loud it is. I know another friend complained that media players often now have the volume capped so that they are less likely to induce hearing loss but are unusable if you already have hearing loss. A Cowon D2 turned out to be loud enough for her to hear. I know videos without captions or podcasts without transcripts are a problem. I don't know what else though.
* Vocab note: A person has an impairment. Society's treatment of that impairment is what disables the person.