I have taken custody of the Lumens to which I am entitled, and have flipped them for BTC. You may well choose to keep the lumens. Here is how it worked for me:
The premise is that the blockchain is frozen as per July 4th. If you had BTC's on that date, and have the ability to verify your address with your private key, you are in business.
Go to
https://www.stellar.org/lumens/bitcoin-lumen-program/
I claimed using a BTC wallet, not an exchange.
It's pretty simple, you will be asked to verify yourself via Google+ or FB. This giveaway (btw) seems not to be open for US residents. Once verified, you will specify the BTC address that you control and verify a specific message using your private keys. Your stellar account will be instantly credited with lumens. From there, I sent the lumens to bittrex (near instant) and sold for BTC.
I found that bittrex gave me the best execution on trading my lumens for BTC.
The total giveaway to BTC holders totals 19Bn Lumen, and will be executed in a phased manner. The current first giveaway commenced on Jul 4th and is open until October 5th, and will cover 3Bn Lumens to start.
Hope this helps some of you as a reminder, if nothing else.