Acer has released Windows drivers for the A150 today and they can be downloaded here. They are not really useful as no AA1s with built-in 3G are available yet, but they do reveal which 3G module will be used. There are actually two drivers included in the package. The first is for the internal Option GTM380 PCI Express module while the other one is for an external 3G USB modem by Qualcomm.
The Network Manager in Linux was already updated with an 3G Option a few days ago, which may actually be referring to the name of the 3G module itself.
Thanks to macles for the heads up.