I will be definitely going along to this with my brother. I've been to both of the previous Silverstone 24hrs, as well as the old Willhire 24hrs at Snett in the early 90s, and they are cracking little events. As Piglet mentioned, there's never going to be a huge crowd for this type of event (I heard it was 93 paying punters in '05), but last year's better weather seemed to bring a few more out to watch.
So, if you see two fellas in some sort of 4x4 Hyundai (which I should be able to blag from work as our 'base' for the weekend), come and say hello. I for one am really looking forward to this!