[Update Friday, May 29, 2015: Skype has issued a hot fix that resolves this issue.]
Skype released an update for their OS X app today, version 7.8.388, that includes a nasty bug: it now ignores whatever audio devices you have selected in Skype > Preferences > Audio/Video. It treats every one of those 3 drop-downs there as though you have selected "Same as System."
Skype 7.8.388 now ignores audio device selections.
For most users this may not matter (in fact, "Same as System" is the default), but for anyone who chooses to use a different set of headphones or a separate microphone for Skype, you're in trouble. If you update to 7.8.388 your only choice is to set your System Preferences > Sound > Input and Output settings to be whatever you want Skype to use. Alternatively you can choose not to upgrade Skype and stay on version 7.7.335.
An additional warning for podcasters or anyone recording audio from Skype: save your working version somewhere else before trying this new one. You may find that your recording software or workflow no longer operates the way you expect and need.
The folks at Skype are aware of the issue and indicate that it will be fixed in a future build, but have not yet offered any timing as to when that might be available to the public.
Thanks to Ecamm Network's post in the comments below, you can still download Skype 7.7.335.