Every message sent after the daily limit of 100 SMS would be charged at not less than 50p, stated the new regulation. Reduction of Limit and other changes are to be effected and implemented within 15 days from now. So you just have half a month remaining to enjoy the Messaging Freedom.
Also there are other regulations to control and curb this menace like sending an occasional message, on part of telecom operators, to its subscribers advising them not to send any commercial communications if they are not registered with the Authority as telemarketer, obtain an undertaking that the SIM or connection purchased by him shall not be used for telemarketing etc. etc.
What ever steps TRAI take, only the common Mobile user would be at the trouble. You can read the full text of the new regulation on this page.