WebSphere Application Server Mobile, dependency injection, migration and coexistence strategy

From a mobile perspective , the new WebSphere Application Server (WAS) Feature Pack for Web 2.0 and Mobile V1.1.0 provides developers with ready-to-use components, simplified, standards based development of mobile web applications, rich Ajax websites, and REST web services. This feature pack can be installed on WAS 7 as well as WAS 8 and contains an implementation of the JAX-RS specification that provides for building RESTful webservices. Feature packs are fully supported by IBM. See whitepaper http://www-01.ibm.com/common/ssi/rep_ca/3/897/ENUS211-143/ENUS211-143.PDF for more details.

For dependency injection we strongly recommend using the Contexts and Dependency Injection  (CDI) specification , part of the web profile in Java EE 6.  CDI provides type safety and loose coupling between POJOs and other EE resources using dependency injection. CDI  (JSR 299) provides context and semantics to the lower level Dependency Injection Specification in Java EE6 defined by JSR 330.   CDI also provides a way to extend the Java EE platform via extensions which allow customers to build custom components and modify EE in a specification compliant fashion. For a detailed overview  and a presentation on CDI see http://dl.dropbox.com/u/12872475/CDI_Impact_2011_RohitKelapure.pdf

The CDI specification is currently ONLY available in WebSphere Application Server v8.  A less desirable option would be to bundle a CDI implementation such as from the Apache Open WebBeans project  in your own application on WAS 7. In this scenario when the CDI is bundled inside the application, IBM will not be able to fix CDI issues as it is a part of the customer application.
For an overview of features in WAS 8 see http://www-01.ibm.com/common/ssi/rep_ca/9/897/ENUS211-139/ENUS211-139.PDF

For migration to  WAS 8  see the following resources
http://www-01.ibm.com/support/docview.wss?uid=swg27008724
http://www.ibm.com/developerworks/websphere/downloads/migtoolkit/vtov.html

WAS 8 can coexist with WAS 7. The links below will  explain mixed cell coexistence, where you can add servers at a  later version of WAS for the new features and keep the production environment stable on an older version WAS.
Running multiple application server versions        
http://publib.boulder.ibm.com/infocenter/wasinfo/v8r0/topic/com.ibm.websphere.migration.nd.doc/info/ae/ae/tins_coexistep.html
http://publib.boulder.ibm.com/infocenter/wasinfo/v8r0/topic/com.ibm.websphere.migration.nd.doc/info/ae/ae/cmig_coexist.html
Setting up Version 8.0 coexistence
http://publib.boulder.ibm.com/infocenter/wasinfo/v8r0/topic/com.ibm.websphere.migration.nd.doc/info/ae/ae/tmig_70coexist70.html
Setting up Version 6.x, Version 7.0 and Version 8.0 coexistence
http://publib.boulder.ibm.com/infocenter/wasinfo/v8r0/topic/com.ibm.websphere.migration.nd.doc/info/ae/ae/tmig_6coexist70.html