MySpace.com clone - is it possible with Ruby on Rails?

Hi, I wanna know wich of the well known frameworks is the best choice
for myspace-clone community website.

CakePHP ? Zend Framework? Symfony?

Ruby on Rails :slight_smile: ?

Django?

or maybe
Kohana? Prado? or something else?

Is it better to use PHP or Ruby or Python? I will pay a webdesigner
for this job, but I want to know which lang and framework is in your
opinion the best for this kind of application.
I expect about 10 000 or more unique visitors each day so I want to
know words from You, the professionals.

It is VERY important that the user can change the CSS, like on
myspace.com.

Then I want to know if is it better to provide for users profile page
this URL
/I have 4 letters in my domain name./

username.****.com

or

****.com/username

thanks in advance