I found it! I thought I'd read somewhere they were going to give it away.
https://steemit.com/bitcoin/@stan/bitcoin-united-btc-u-offers-3-second-confirmations-and-massive-throughput

Relevant portions:

BTC-U will be gifted one-for-one to all holders of BTC at the last unforked “classic” block when the Time of Forking inevitably arrives (we won’t fork it over until somebody else breaks the taboo – then it will happen automagically).

On the day the fork occurs, BitShares will grab a “snapshot” of the state of the Bitcoin blockchain. Shortly thereafter, BitShares will distribute matching BTC-U to every BTC owner on the BitShares blockchain. All you’ll need to do is import your bitcoin keys into the BitShares wallet and claim them!