Spring Web Services is a product of the Spring community focused on
the creation of document-driven, contract-first web services. The key
features of Spring Web Services include...

* Making the best practice the easy practice: Spring Web Services
makes enforcing best practices easier. This includes practices such as
the WS-I basic profile, Contract-First development, and having a loose
coupling between contract and implementation.

* Powerful mappings: You can route an incoming XML request to any
handler depending on message payload, SOAP Action header, or XPath
expression.

* XML API support: Incoming XML messages can be handled in standard
JAXP APIs such as DOM, SAX, and StAX, but also JDOM, dom4j, XOM, or
even marshalling technologies.

* Flexible XML Marshalling: The Object/XML Mapping module in the
Spring Web Services distribution supports JAXB 1 and 2, Castor,
XMLBeans, JiBX, and XStream. Because it is a separate module, you can
use it in other environments as well.

* Reuse of your Spring expertise: Spring-WS uses Spring application
contexts for all configuration, which gets you up-and-running quickly.
Also, the architecture of Spring-WS resembles that of Spring-MVC.

* Support for WS-Security: WS-Security allows you to sign SOAP
messages, encrypt and decrypt them, or authenticate against them. And
it integrates with Spring Security.

Reference:
http://www.springframework.org/node/507