You can now download Adobe Camera Raw 5.4 (LightRoom 2.4 Raw module) with support for the Nikon D5000 and lots of other cameras:

Newly supported cameras for Camera Raw 5 and Lightroom 2:

Support for the following cameras has been added from Camera Raw 5.3 to 5.4 and Lightroom 2.3 to 2.4

Canon EOS 500D (Digital Rebel T1i/EOS Kiss X3 Digital)
Canon PowerShot SX1 IS
Epson R-D1x
Hasselblad CF-22
Hasselblad CF-22MS
Hasselblad CF-39
Hasselblad CF-39MS
Hasselblad CFH