As you can read there both Twitter and Firefox will soon support OAuth. For Twitter is actually is strange that it isn’t there already because Twitter devs have been part of the specification group. But better later than never and I am very much looking forward to it.
As for Firefox I wonder how an OAuth implementation might look like. OAuth is used to do authorization between services so I wonder how the client can play into that. Looking forward to hear more about that.
What also was mentioned in that article (and I still have to check this out) is an OpenID implementation for Firefox done by Vidoop. That’s even cooler and this was also discussed in many places already (e.g. during Barcamp Berlin/Web2.0 Expo with the guys from Flock).
All these things are good building blocks for building an open web (actually even open internet as I am also looking into how to use OAuth for the Open Grid Protocol) and making your data more portable :-)