Just got an email this morning titled:
Start scratching, <name> to reveal your Mystery Deal!
Load the page, digitally scratch off your battery reward and apply it to your Best Buy Credit Card account. I received an offer for a $25 reward certificate after spending $250 at Best Buy in-store or online. (edit: thought it was outside of Best Buy, turns out it has to be at Best Buy stores)
Must complete the spending requirement before Sept 27.
Edit: Some people are receiving a 10% coupon off one item.
The rewards on this card are just crazy good in my opinion.
QA Note: YMMV, http://www.bestbuy.com and log in to look at reward offers