As it's become a pretty hot topic this year. Here's a thread for it. Please add your own tips and tricks for return and rebuying.
Buy the item in advance of the sale. Return the item to the store on Black Friday and then immediately rebuy it to take advantage of the new sale price.
In a lot of cases, Black Friday items have rebates. So you must actually re-ring the item to get a new receipt with valid dates for the rebates. Also, make sure you buy the item within the retailers return policy or they may not allow you to return and then rebuy. These policies can vary anywhere from 14 to 30 days.
This method could also be considered useful for stores that don't allow pricematching.
Potential problems that you should be somewhat aware of:
1) Some items may not be bought early as some stores hold their stock of the item until Black Friday. As a way to prevent early buying.
2) Some managers may not allow you to rebuy the item or even pricematch the item citing a special limited one day event.
Pricematching discussion thread in case that's what you're looking for.