It's about Obama's citizenship. The focus of the lawsuit is that Obama's mother did not meet the legal requirements for Obama to be an American citizen at the time of his birth. His father was not an American citizen, and there's also the question of whether his father had him naturalized as an Indonesian citizen before his 18th birthday.
When Obama traveled to Pakistan in the 80's, he went there using an Indonesian passport because it was against US law to enter the country using a US passport.
This has been kicking around for the last sixty days. If it was going to make any waves, it would have done so by now.