A quick update on Skype: the next Skype version will include native PulseAudio support. And not only that but they even tag their audio streams properly. This enables PulseAudio to do fancy stuff like automatically pausing your audio playback when you have a phone call. Good job!
In some ways they are now doing a better job with integration in to the modern audio landscape than some Free Software telephony applications!
Unfortunately they didn't fix the biggest bug though: it's still not Free Software!