I have just got in from work to find it has been reduced to 120 seconds, much better indeed.
There have been some good ideas suggested here how to deal with it, and as Frank says, 120 seconds will do for now, see how that goes, maybe it will reduce in time if the serial posters back down a bit.
It is not just JetBlast that it is happening in, some mods have reported some users in other forums as being a bit trigger happy too. Thankfully, our forum here is pretty much safe from these kind of people and the people who do post a lot here, and there are a few, post constructive, well balanced, helpfull posts and it is easy for us all to see why this 300 second thing has annoyed most of us here.
I think by now the serial offenders will have been emailed by the admin to ask them to curb their posting habbits and the 'probationary user' function is serving us well at the moment too, a bit of a hassle for the new user to wait to get the posts verified as and when myself or Keygrip get around to doing them, but generally this method has stopped the spammers advertising as they used to. No one wants to come to this forum to read how to buy cheap phones, ipods, fake watches or loose weight or such so probationary user issue is not a bad thing.
Regarding the chat room, this has been done before. It did cost a lot of money for the licence to operate an exclusive pprune chat room, I think it was around a thousand pounds a year or so and it ended up with most of the chat room users there contributing out of their own pockets to keep it running. This came to an end though as most people, the regulars there, were in touch via msn or similar anyway and the chat room was eventually dropped.
Thanks for the responses chaps, as I say i was just curious as to what everyone thought of all this, me asking for your opinions is just that, not an offical ask by the site owners.