Open source intelligence is simply intelligence gathering based on overt (as opposed to covert) sources, such as the news media. The beauty of it is that both you and I can practice it, with an eye for actions which indicate changes of hearts, motivations, and capabilities.
The recent revelation by Indian investigators that homegrown terrorists likely abetted Pakistani ones in the Mumbai attacks shows well a change of heart and a change of tactic by Indian leadership. Originally, New Delhi took a hard-line on Islamabad following the attacks even though the degree of responsibility of militants in each country was unknown, The motivation for this stance was largely political, with Indian leadership looking to both placate their populace and position themselves to have the upperhand in Kashmir. This most recent discovery, in all likelihood being well founded, is not just publishing of fact but is also indicative of a change in tact in which diplomacy is the desired mode of solving this crisis. For strategic reasons, the story of these two homegrown terrorists could have been either hidden from the media to keep the pressure on Pakistan or widely touted so as to simultaneously indicate to Pakistan a change in tack and also to appease the Indian population that Pakistan was not solely to blame. With the second approach taken, it should come as no surprise that the Indian foreign minister has most recenltly ruled today (1 2) that military confrontation was essentially out of the equation as the standoff continues.