We are indebted to bondegnasker in the comments here with this report on the 14..Bb7 move in the Meran with which Anand won games 3 and 5 of his world championship match against Kramnik. Like many, I wondered at the time if we would ever find out who exactly came up with the idea. Perhaps it was better to ask, "who didn't?"
This just in from the Danish chess federation's magazine "Skakbladet", Peter Heine Nielsen commenting on Anand's 14...Bb7 in game three of the match (my translation):
The move is no novelty, but its reputation is so much poorer than 14...b4 and 14...Ba6 that it apparently came as a total surprise to Kramnik. Up until now everybody was of the conviction that developing the bishop to its most natural square and pretending that Black had an attack was just an unrealistic dream, but Anand shows that it is reality. Who invented it? Well, Kasimjanov prepared it for his meeting with Gelfand, but Anand had also found it. I recall a hint of disappointment at the first training session, when both Kasimjanov and Anand said that they had great ideas in the Meran and it turned out to be the same. But when we started analyzing it, disappointment quickly turned to joy."
Not much to add to that story, really. Great minds think alike! My guess is that Heine may have played a bigger role than he claims!?
Perhaps, since Nielsen has worked with so many top players. I assume the encounter he refers to was Kasimjanov's June 2007 candidates match against Gelfand. Unfortunately for Kasimjanov, who went on to lose that match after epic tiebreaks, and fortunately for Anand, Gelfand played 9.a4 instead of the 9.e4 main Meran line Kramnik went for. (When they met later in 2007 in the world blitz in Moscow, Kasimjanov played the Albin Countergambit against Gelfand. I guess he couldn't convince Vishy to try that one.)
Update: StefanLoeffler in the comments adds that Anand credited Kasimjanov for "most of the work" on the innovation in the interview he did with Anand for Frankfurter Allgemeine Zeitung that ran on October 31.