hi satheesh,
* Rails is Web 2.0 ready.It can provide an easy way to implement AJAX functionality specific to the Web 2.0 trends.It also has an emailing framework built in, web services and caching.

* Ruby code is easy to test and fix because of it's built-in testing features.If you're using Rails, it will automatically create basic tests for you that you can later expand if you wish.The less time you need to spend on these processes, the more productive you'll be.
* Test cases can be easily planned and ran with "harnesses" and "fixtures" and then deployed automatically with "rake" that you can get here.In fact, with Rails you get separate environments for development, testing, and production also.

* Rails uses code generation and metaprogramming also,unlike other frameworks which mainly rely on code generation.Metaprogramming allows the use of programs to write other programs.You can get more info on metaprogramming concepts here

* Rails is open source.This means that it can be easily improved,modified,have bugs fixed.Newer,better distributions of it generally can appear at a faster rate than it happens with other proprietary-code frameworks,because open-source allows others to contribute.