Q: Lightning: How to use Custom Labels inside components? What is the way to use localized labels from Custom Labels or from field config inside lightning components?
In VF it was possible like:


*

*$ObjectType[sObjectName].fields[fieldName].Type

*$Labels.Custom_Label

A: In Lightning Components, these are called global value providers. Currently there are only a few, including $Locale, and $Browser. 
Some of the very useful global variables that exist in Visualforce such as the two you state and others like $User, $Profile, and others have not yet been implemented in Lightning Component Framework. 

A: This feature has now been added as of Summer '15
https://developer.salesforce.com/docs/atlas.en-us.lightning.meta/lightning/labels_value_provider_platform.htm

A: I have the same requirement, what I did mayn't be the optimum solution; but it does suffice my requirement.
I had created a CustomLabel csv file and uploaded as a Static Resource.
Hope this will help you too.
