It's still on their list of supported file types, so it may be worth a second try.
Then again, the .pub support may have been permanently removed for some reason. E.g.:
- Converting that file type represents a high workload, so it's reserved for paying customers
- There's a bug in the conversion engine
- There's a dispute on licensed material, and they're legally required to suspend the service until that dispute is resolved
If any of the above applies, there should be a statement to that effect somewhere on their pages. Can't see it anywhere, so chances are that the .pub support will reappear. A temporary lack of support may be due to a conversion engine update. It might also be that your file is of a newer format than the service supports. (Publisher storage format has had somechanges, and I recall instances where new versions couldn't read old files.)
OOo 3.3.0 and Apache OOo 3.4.1/4.1.1, on Ms Windows 7/8 and Mac OS-X.