http://news.com.com/Microsoft+offers+development+tools+for+Mac%2C+Web/2100-1007_3-5867417.html?tag=nefd.lede (http://news.com.com/Microsoft+offers+development+tools+for+Mac%2C+Web/2100-1007_3-5867417.html?tag=nefd.lede)
Apparently you will be able to write code to run on Mac's and Windows in XAML.