Sony have previously stated that the psvita 3g would be region locked. However it's only now that over zealous importers are realizing the consequences of their actions. Having paid a nice premium for the device many will be dissapointed to hear that they will not be able to use the 3g features of their overpriced imported psvita's.
According to Anne Natsuki, Asian and Japanese units won’t work in the US, Europe or Australia due to 3G region locking. Apparently prices of the units have already started to drop in Hong Kong now that people have taken notice.
Anne recommends that it’s probably best for everyone wanting 3G to just wait for a localised release, although there are possible workarounds. The problem with these, however, is that they can be complicated, risky or even costly. Anne also says there’s a possibility of the Hong Kong version of the console being compatible in Australia, but that’s yet to be confirmed as it’s not released until later in the week.
So, if you were thinking of importing a Vita 3G early - it’s probably not a good idea. You might be happier just buying a unit with WiFi and buying a dongle or similar wireless tethering device in your own country."