Unquixotic

Who offers it?

CompUSA, Albertson’s, Amazon (via Circuit City & Borders), Linens ‘n Things, Circuit City, Best Buy, Wal-Mart (limited products), PartsAmerica, HP’s Snapfish (via Walgreens), and Sears to name a few.

Oh yes, and your friendly neighborhood WWDB IBO affiliated with Quixtar.

Amazon in particular specifically set out to form product pickup agreements with Borders and Circuit City in order to offer the service, and HP did the same for their Snapfish agreement with Walgreens.

Who takes advantage of it?

According to Forrester Research, who considers the practice a trend for "Advanced multichannel retailers," those using the service are NOT Luddites:
"73% are technology optimists, and they spend 44% more online than the
average consumer . . . In-Store Pickup Users Are Savvy Online Buyers"