The media often likes to portray the Vegas, or any market, as overbuilt by home builders. That's a bit of a misconception. They had been reacting to demand, and at one point couldn't keep up. Not that long ago there were some developments around Las Vegas holding lotteries for building lots, and a backlog of pulling permits.
The builders also reacted when the market slowed and by late 2006 already began reducing inventory here in the valley. Since then they they've whittled down their home counts, passed on land options, and what had been previous market based months of supply is now usually measured in weeks based on today's levels. While there is still standing inventory to chose from, the industry has primarily gone with price reductions, keeping pace with the general lowering of market prices caused by foreclosures. Those foreclosed properties are where you find the oversupply.
Combine healthy price cuts with tighter credit standards, and like the others have mentioned, I doubt you'll find any builders offering a second. The piggybacks have had a much higher default risk and a big part of the suicide loans that triggered nationwide housing declines in the first place.
In general, what I've been seeing more of for Las Vegas real estate sales is FHA / VA loans with their allowing seller incentives toward closing costs and down payments. The recent influx of $200 billion into the mortgage market through Fannie Mae & Freddie Mac has not only added liquidity to the lenders, but has 30 year fixed rates sliding under 6% in the last 2 weeks. These items with the lower pricing across the board is what I believe is causing the increased activity here in Las Vegas.
Sveral analysts are saying that if Las Vegas housing hasn't reached bottom, it's close. This article mentions that, and the typical local builder incentives being offered.