If anyone coming to the conference has an extra $10 little Macbook-pro-retina-to-every-other-mbp-in-the-world power adapter (a.k.a. a "MagSafe to MagSafe 2 Converter" [1]), or will be passing an apple store and can pick one up, I would not only reimburse you, but reward you in powerful belgian beer :) I forgot my power cord, and just realized that my laptop is totally incompatible with everyone else's...
Thanks,
Sean
[1]
http://store.apple.com/us/product/MD504ZM/A/magsafe-to-magsafe-2-converter
Cheers,
Sean