If you want to have Skype 2.8 work on your new Mac Book Air you need to take one step back and then go forward.
Basically, you have to uninstall 2.8, delete an xml file from your user library, install Skype 2.7, make sure it works, then install 2.8.
Skype is promising a hotfix according to folks on the dev team, but until then, just take those steps and you can have it working.