Wow, 1200 resumes for 3 positions, I didn't know that getting recruited by Google was that competitive, good for them that they can afford being that competitive.
Do you mind telling us if in the first interview you aced all your interviews, because I surely didn't.
The selectivity numbers I've heard for the whole process are about 1:2000, with about an order of magnitude decrease for each stage of the process (resume screen, phone screen, in-person interview, hire).
Keep in mind that like most statistics, these are misleading. Google gets a lot of applications from people who just want to work at Google and have no relevant skills, or who may be friends/SOs of current employees, or who ping their local Googler on Reddit or HN to submit their resume. These go into the system because who knows, we may find a gem, but realistically they have about 0 chance of being hired.
Getting to the in-person interview stage basically means we have reason to believe that you're a competent software engineer, but the acceptance rate is still something like 1 in 10 or 1 in 20 from that point. It's tougher than getting into Harvard and roughly on par (perhaps a bit easier) than getting into YCombinator.
Do you mind telling us if in the first interview you aced all your interviews, because I surely didn't.