Well, consider it fortunate or unfortunate, but the background investigation was conducted by folks within the Democratic Party, and "sources within the party" have identified "researchers connected to Senator Clinton" as the instigator of the investigation.
"In late 2006, when the Illinois senator demonstrated his intention to run for president, the Clinton campaign ordered a background check on Mr. Obama, the sources said. Earlier this week, Mr. Obama established an exploratory committee, the first step toward a formal race."
Now you can take "sources" to mean that her hands are clean of this if you like. Personally I highly doubt anyone would be pinning it on her if there wasn't a good chance its true. I could be wrong. Considering he is the best threat on the boards to keep her from even running, I'd probably have done the same in her shoes. Heck, I think it needed to be done. He's the one who made a big deal last year over his trip to Kenya and his ties to his father's family there. The fact that he never bothered with them until he became a political bigshot who got to speak at the national Dem. Convention is irrellevant. He brought it up, the history is fair game for dissection. If there are things he'd rather NOT come out, his bad.