Name: RT5390 [802.11 b/g/n 1T1R G-band PCI Express Single Chip]
This chip is located on a half-size mini PCI express card in a new (2011-02) HP Pavilion dm1z-3000 notebook, which indeed supports 802.11 b, g, and n and contains a half-size PCIe wireless card.
I'm guessing this chip is the RT5390, or a variant thereof (perhaps specifically for HP). The name in brackets is taken directly from the PDF for the RT5390 found on the Ralink site.
My guess is based on the the pattern of device IDs for their newer (RT3090+) chips, plus the devices supported by the HP driver for this computer (RT5390, RT3592, and RT3090). The driver can be downloaded from the HP website, but right now I can't extract it completely to get to the .inf files.