DH read something about this incentive recently (or maybe he saw it on that show on the Travel Channel?). The way it works is that yes, they do allow you to apply the amount you paid for your on-property room toward your down payment, so your current trip is like "using part of your DVC membership". However, they do deduct the points from the contract which you buy. Let's say, for argument's sake, you stay at Pop Century, which is a value resort. You go on the tour and you buy, for argument's sake, a 200-point DVC contract with this incentive offered. Well, since DVC does not offer Value resorts as an option to stay on points, they "charge" your membership the same points it would have cost you to stay at a moderate, as written in the Dream Book on the Disney Collection points chart. If you stay at Contemporary, they will deduct the points it would have cost you for that, and so on. So, is this a good deal? IMO, hardly...the non-DVC WDW properties are many more points than staying at a DVC resort. And it certainly does not seem like a deal if you are staying at a Value but they have to take points for a moderate. So, what Disney is doing is yes, helping people spend less money in these hard economic times (if you are put on the spot and are being told your current accommodations will be "paid for" it seems like such a great deal, kind of like those $199-for-5-nights-but-sit-through-3-hour-presentation deals), but remember, although it is not costing the person extra money to stay on property AND purchase DVC, it is ultimately costing that person points.
So, if that 200-point contract purchase with this incentive ends up costing that person 400 points to get that incentive, there goes this year's points plus next year's from borrowing. That means no DVC vacations on points for at least one year, and if that person wanted to use all 200 plus borrow for their trip they would have to wait even longer. Or wait a while to catch up at least. So if you are not planning to use a lot of your points right away, yes, this could be a great deal. But if you want to take advantage right away, it really is something to think about whether or not it is worth paying maintenance fees and waiting a year or 2 to use your membership.