Here is the link - http://keralartconline.com/
Finally our kerala govt has caught up with the rest of the states. Only thing to be seen is whether this will be a case of the classic "too little, too late". I got to know it from this obscure article in The Hindu.
The site offers booking for some 180 bus services including for intra state transportation.How many will avail of this service is something that remains to be seen.
The booking for inter state services seems to be good.With the fare far below than what is offered by other bus services. I have not tested how robust is the site with transactions. Or what are the means through which transactions can be done - net banking or credit/debit cards.