I have observed the following as part of testing 9.0.1, perhaps any of these may save you time if you are testing out scripts and/or tapping into views on the PG internals and/or doing monitoring.
1. tabcmd is now case sensitive. It works smart and fast, just be aware that it seems that it's been rewritten and is now case sensitive to be all lower case. Not a big deal, it's just worth noting.
2. In 8.3, the workbooks and datasources table would get a new id and a fresh created_at date when publishing new content. This seems to no longer be true with 9.0. I have a couple scripts that were tapping into the created_at to identify the recently published content. The better way to do this is to tap into historical_events and look for published events.
3. The acceptable values for statuses have changed for doing Enterprise monitoring. We used to have to only look for "OK", now we have to look for a few other values (which are documented in the admin guide).
b. The permissible statuses have changed from “OK” to possible permissible statuses of “Active”, “Passive”, “Busy”, “ReadOnly”, “ActiveSyncing”. If you add in these 5 to the existing script, it’s fine to just leave “OK” in there as well.