This is the third time in two years that Monster.com has been compromised, the last coming at the end of 2007. What makes this new attack particularly interesting is that after the second attack, the site promised their customers an increased level of protection of sensitive data. Whether those heightened security measures were never put in place or were ineffective isn't mentioned.
Any reassurance Monster might give at this point will probably be ignored, as obviously the company has issues with security. I for one would have a hard time signing up with a company that has such a bad history of data breaches.