I've merged the DECT tree with the Linux 3.1 release and pushed out experimental support for P640j (Wideband) in the MAC/DLC/NWK layers. Besides the kernel, libnl and libdect need to be rebuilt (Build instructions).
Asterisk wideband support is still unfinished and chan_dect will currently not build cleanly, only update if you intend to work on chan_dect yourself or want to play with wideband using the libdect example code.
I've pushed out P640j/wideband support, so far only for the 1442x firmware, the upper layers still need a bit of work. P640j can only be enabled if the PCMCIA driver is deselected and requires a firmware rebuild. I'd appreciate feedback whether things are still working properly on the PCMCIA devices.