Philip Rosedale himself sent out an email giving full disclosure of the incident.
What information was leaked:
- User names
What Information was NOT leaked
- Real Life Names
- Credit Card Details
- Pay Pal Information
Read the full text here
At this time it's not known who was behind this. Before you jump to the conclusion that it was some Secondlife Script Kiddie, remember this is a very competitive area of business right now and it could much more easily have been one of his many competitors.
If you had an account at High Fidelity, I wouldn't be very concerned as it doesn't appear that any really sensitive information was leaked.