Apple has seeded iPhone 2.2 Firmware Beta 2 and has fully enabled Google Street View. We had previously reported that Beta 1 of iPhone 2.2 had hidden APIs related to the Street View for Google Maps, but was not enabled.
Apple seeded iPhone 2.2 Firmware Beta 2 to developers tonight. The seed notes also indicated that Line-in audio accessories are now supported in the SDK.
Update: iPhoneYap has posted a gallery.