Last year Microsoft launched new email service Outlook.com and also acquired Skype, and now Microsoft has launched a preview version of Skype for Outlook.Com. This allows you to make voice and video calls to your friends from Outlook inbox beside of sending IMs.
The preview is being rolled out in United Kingdom and soon will be rolled out in USA and Germany in upcoming weeks. This service will be made available to all users in coming months.
To use this service you need to install a plugin for your browser, which will be available for IE, Google Chrome, and Mozilla Firefox, after which it will connect Skype with Outlook.com using Microsoft account.
Once you had connected both account then you will be able to see online users under messaging option and will be able to send them message.