Some highlights from the release notes:
Object-oriented C++ APIs enable external code routines to run inside the Firebird engine space, including (but not limited to):
Stored procedures, triggers and functions (e.g. in ObjectPascal)
Encryption schemes for data
User authentication schemes, including secure key exchange
A true BOOLEAN type
IDENTITY type (aka autonumber on other dbs) - no need any more to define your own trigger+generator/sequence to get an auto ID number
One single library for both embedded and client/server operation