Microsoft’s ad blitz for Bing is still going strong, and it’s starting to hone in on a new target: your wallet. Bing’s latest TV ad, which aired for the first time last night, is focused on Bing Cashback, the program that allows users to save money when they purchase items found using Bing search. Cashback has been around for a while, most people probably had never even heard of the program until now. This is the first time Microsoft has ever aired an ad for Cashback, and you can be sure that it’s going to strike a chord with plenty of viewers.

Microsoft launched Cashback on its old search engine, Live Search, in May 2008, when we called it a “desperate and brilliant move” to trade search revenue for market share. As it turned out, Cashback failed to do much to improve Live Search’s market share last year, but it did result in a significant increase in advertising revenue. Now that Bing is picking up some steam, CashBack may turn in to the traffic driver Microsoft originally envisioned.

To help drive more interest to Cashback, Microsoft launched a limited promotion on August 10th called Double Cashback, during which Microsoft would match the amount of the rebates being offered by retailers (e.g. if Nike normally offered a $10 discount rebate, the promotion would give them $20). That special turned out to be too successful — it drove so many sales that Microsoft wound up ending it three days early, after distributing the maximum amount of money Bing had allocated for the promotion.