correction .. the Symfony2 serializer does not support serialization groups, the JMS Serializer does.
in case you have not yet used the JMS Serializer. basically it allows you to add mapping definitions for your models. these mapping definitions specify if properties should be included when serialized and with what data type etc. every mapping can optionally have a list of groups associated. then when you serialize you can specify from which groups do you want to include mappings.