Unfortunately, I joined too late to be actively involved in organising the next SPA conference (London, June 12-15th 2011). That responsibility lies with Ivan Moore and Mike Hill as conference chairs and Willem van den Ende and Rob Bowley as programme chairs. However, I'm definitely going to attend the conference having just snapped up an early-bird ticket.
What I like about the conference is that it's not oriented around a particular technology or approach, and the attendees tend to be at the expert end of the scale. In my opinion, it's the best conference having your thoughts challenged. That's what I want from a conference.