"It's a private meeting Keith"
First of all, assuming reporters are going to keep a private meeting secret is kind of like assuming what is said in a Liberal caucus meeting will stay secret. The Ottawa press gallery is one giant clique so of course they were going to tell each other about it.
And, given this, how did Harper's crew expect the non-chosen ones to react? If there's one thing the media love more than process stories, it's process stories about the media. And they were all over this one. You can read some very amusing recaps here, here, and here. And I bet Keith Boag had as much fun putting together this piece as I had watching it (Carole: "Can you imagine why some reporters were invited and others weren't?" Keith: "No Carole, I have no idea at all").
And I'd say judging from the newspapers and TV coverage so far that this attempt at media controle hasn't exactly gone according to plan...