Well india and indians always continuesly blame Pakistan for every mishap in india now that its the other way around why "mirchi laghi?", i ask myself.
The difference of course is that India meets the burden of proof that's placed on it, as an accuser. Looking specifically at the Mumbai attacks, American NSA and Chinese MSS both intercepted communications between the jihadis carrying out the attacks and their handlers in Pakistan. The recent arrest in the US of Dauood Gilani (aka David Headley), further validate the Indian position.
Pakistan never raises this outside of the Pakistani media. No evidence is presented to anyone. Even China no longer placates the Pakistani position. One is led to believe this is for internal Pakistani consumption.
There is growing consensus amongst Indian analysts that Pakistan should do whatever it needs to combat the extremism that's boiling within its borders. If it means blaming India to garner internal support for actions against organizations that were created by the Pakistani state, so be it.
There is also, of course, a fear that Pakistan will be chasing a phantasm. Looking for non-existent Indian culpability means that the terrorists will not be dealt with.