I've been doing a little research:

Pretty much all the digital processing chips out there are already using 32-bit data lengths. In the case where 24-bit DACs are used some of the data is just not sent to the DACs.

Cirrus Logic has an 32-bit Audyssey processor chip (CS48AU2) with built in algorithms. The interesting note on the data sheet was that Audyssey algorithms only support 48, 44.1 and 32 KHz data rates.

AKM Semiconductor offers the AK4390 32-bit DAC which is used on the Esoteric SACD SA-50. For $5,000 you get a 130 dB SNR.

Wolfson has the WM8741. (See ARCAM products)

TI/Burr Brown has their PCM1795. On paper it is not as good as the AKM or Wolfson, but there's a lot of other factors to be considered.

These all seem to be in production, mainly in high end SACD players.