Straight from the Android's mouth:
Source:
"cupcake" development branch ?(Android Open Source Project)?
So essentially there is a Cupcake Development Branch. There is no "cupcake update" but the CDB is working on a bunch of highly anticipated features (like onscreen keyboard, stereo bluetooth) and they will roll them out as they become available. It's confusing because so many, even bloggers, refuse to make that distinction.
Yes, the features are being worked on.
Yes, they will be released in future updates.
NO, there is no one, singular, all-encompassing "Cupcake Update".
If you got RC33 you already got one CDB Feature, the ability to save MMS attachments.