Eric Schmidt said the following at Mobile World Congress in January:
“We have an OS called gingerbread for phones, we have an OS being previewed now for tablets called Honeycomb. The two of them… you can imagine the follow up will start with an I, be named after dessert, and will combine these two.”
The speculation is that it would be ice cream or ice cream sandwich. It is now just about confirmed from the following reply on the AOSP issues forum:
A bug fix will be provided in Ice Cream Sandwich.
We are not sure when Ice Cream Sandwich will be released, but we hope to see it at Google I/O. Stay tuned, as we will let you know as soon as we hear it.