This advice is posted to HN quite a bit, this is the same reason websites have press kits available. Long story short, journalists are lazy, just like the rest of us, and they have deadlines, just like the rest of us. Exploit them to your advantage and help them out at the same time, and if you are especially different, they will love to be the first to report.

Speaking of that, be careful about who you send what when, a lot of people will break your story before you officially release something just to say they were first, and then your site will be offline and all that traffic will be for naught.