Not sure if I will be able to make it myself, but was surprised to not see it mentioned here...
I went to the Official Silverstripe London meet earlier in the summer (as advertised on the Silverstripe Blog - with real Silverstripe staff in attendance!) which was great!
I'm assuming this "regular" meet has sprung from that idea (if that can be called "regular" - it seems they've only had one previous meet so far). I know someone who went to that first one, and he said it was good.
Anyway, I finally got round to joining the Silverstripe forums.... I've lurked here quite long enough!!!