Twitter search is becoming more intelligent and powerful. Google Search is becoming more social.
And here's an example of Facebook doing both:
search displaying on-and-off Facebook content organized by your friend's like's & activity. This is highly useful: using your social graph and the "like graph" to filter beyond Facebook. In a way, it's Google's +1 vision.
Search is changing. And it's happening from different perspectives (Twitter:real time; Google: applying social to core; Facebook:leveraging the social + like graph). Fascinating to watch and each has its own merits depending on the circumstances / needs.