Unless your Flex 2 project has to go to production this month, switch to Flex 3. Now. At least I’ve convinced my client to do this a month ago. Flex 3 final Beta days are  almost over and it brings you lots of goodies.  These are some of the features I like the most:

•    Make your SWFs smaller by externalizing the  Flex framework classes. Split your application into multiple  modules or libraries and keep them in several Flex Builder projects.  Link the Flex framework classes only in the main project . For all other projects select External linkage for the Flex framework. Technically, you are saying to the module, “Do not worry, by the time you’re loaded, Flex framework will be already there”. This will reduce the sizes of the module’s SWF’s or libraries SWC’s.  It gets even better, now you may select the signed framework’s libraries (swz). Flash Player will cache the versioned framework libraries on the client’s disk, and  regardless of which URL was the origin of this cached version, if your application uses the same build of the framework, it won’t be reloaded from the remote site.

•    Advanced datagrid has lots of extras, for example:
 OLAP component – create your cross-tab reports with ease;
Create a datagrid column with a tree view inside;
Multi-column sort in the datagrid
Column totals and more

•    Improved layouts – now you have constraint rows and columns inside containers with absolute layout

•    Bookmark the states of your application using deep linking with BrowserManager

•    Graphical skinner and transitions inside skins

•    Drag and drop the data onto the chart container and it actually draws the chart

•    Collections with GZip compression

Flex Builder has only minor improvements.A notable addition here is all new profiler. You get an extra button on the toolbar that should help in identifying memory leaks and performance bottlenecks. I did not have a chance to take it for a ride though.

Visit  this Web page for the overview of new features of Flex 3. As promised, Flex 3 will become fully open sourced with available nightly builds, access to the source code repository, et al.
And, of course AIR 1.0 will turn your Flex RIA into a mixed Desktop-Internet application (let’s call it DIA). Visit this site  for more information.  Even though AIR 1.0 has not been released yet, there are lots of applications already created with this exiting technology – just go to the showcase page to see what NASDAQ, eBay and other companies have to show today.

A large group of small and mid-size  businesses will enjoy free implementation of AMF communication protocol named BlazeDS.

If you are still thinking of using AJAX of JSF for your data intensive business application, just stop it, will you! Do not spend half of your project’s time trying invent your version of  a data grid with embedded tree or a fancy dropdown, fighting with the browser incompatibilities and slow communication protocols. You can’t afford to be in the Google state of mind. Your human resources and the budget are limited, and your enterprise is not a software development company. Just take care of your business with Flex 3, AIR, and BlazeDS.