I have a Gingerbread 2.3.4 powered Nexus S and I recently got some writable NFC tags. So far I can read them as blank tags
NXP's tagwriter is a great application for writing tags.
My company, which has an application for encoding and managing tags in the cloud, recently held a workshop in Seattle walking developers through the process of reading and writing NFC tags in Android.
The blog posts for reading and writing NFC tags walk through code and have supporting video clips from the actual workshop.
Hope this helps some developers get started with NFC!