I'll start by getting the irony out of the way. In the building where Faraday invented electricity (stretching the truth only slightly), why was it so hard to recharge a mobile device? Thankfully, speculation that Solo09 was an plot by Susan Greenfield to lure all the science bloggers to the Royal Institution so that she could arrange an "accident" to befall them was unfounded (surprisingly, she didn't put in an appearance).
I didn't physically attend the meeting last year, but I did participate actively online, and it was noticeable that after a brief flurry of activity on Twitter in the morning, almost all the activity switched to Friendfeed. This year, there was probably more online activity than last, involving both physically present and remote participants, and much more evenly split between Twitter (which had a more casual, chatty feel) and Friendfeed (more of an archive from the physical participants). This was in spite of a request (which was observed as far as I could see) not to comment on the content of the first talk of the day, which consequently also derailed the Second Life stream (which people had paid £10 for). In general, the performance of Second Life through the day confirmed my opinion that SLIsPants, and I felt that remote participants would have been much better served by a video + slides stream, such as an Eluminate-type interface.
Overall though, the meeting was a great success and much kudos is due to the organizers, sponsors and speakers. it is planned to hold a similar event next year, which I would very much like to attend if I am able to, especially if the idea of a science education strand comes to fruition.