AX 2012 supports attributes for classes and methods. There are quite a lot of attributes provided out of the box, mostly in AIF, Services, Upgrade, SysTest areas and it is also possible to create new attributes by inheriting from the SysAttribute class.
Attributes can really simplify many frameworks. For example, in the upgrade framework initPreSyncJobs() and initPostSyncJobs() methods, that contained usually quite a large amount of upgrade jobs and dependencies registration code, were effectively deprecated. All the registration is performed now via attributes that are attached to upgrade methods.