Nexus One firmware is still at Version 2.2.2 and looks like it will still take some time before we get the Gingerbread version. Google is still not making the Version 2.3 firmware available to Nexus One. Only the latest Nexus S is getting the Version 2.3 firmware.
Apple do things differently, they will ensure all iPhones(old & new) get the necessary updates. Google need to ensure that the Nexus S and old Nexus One both get the updates to the latest android software.
Nexus One users will have to use their Version 2.2.2 till an update is available for them.