Press release.

NH-U12S spec page. Tower (w/o fan) is 45mm deep compared to the NH-U12P SE2's 71mm. Thin is apparently in. $65.

NH-U14S spec page. $75.

I'm intending to upgrade from current Q9550@3.7GHz/1.2V to Haswell in summer so I'm definitely interested in seeing results for NH-U12S compared to NH-U12P.

If size were same one additional heatpipe would quite surely give advantage at least with higher heat loads.
But now heatsink is inch thinner in depth with considerably denser fin spacing (~50 vs ~35 fins) for trying to prevent loss in surface area and in capacity to transfer heat to air.
20 grams lighter weight with extra heatpipe hints there's been at least some loss of fin area.
Then again smaller depth should improve air flow between fins while denser spacing fights to slow air flow.
Going to be real interesting results.

Hopefully we'll see them soon in SPCR's test lab.