Google Webmaster Tool gives all the information about the site which verified by GWT. I want to know that how many sites can be handled by one GWT account ?
Till now I am using 15 sites/blog . Google has not given any limit. so don't worry and keep verifying your sites with google.
I think it should be "as many as you desires". GWT has never stated any limitation officially nor unofficially neither.
I have found an answer confirmed by Google Employee Jonathon Simon: You can read the topic here @ Google Forum: http://www.google.com/support/forum/p/Webmasters/thread?tid=152757e0aeefd2fd&hl=en
We have thousands of sites, 2 years ago a Google rep told me to open up multiple accounts to handle the issue, the limit was 500. A eal pain in the ass
This is true. There has been no post-it that limits webmasters from adding a lot of blogs on it for monitoring.