Last week we discovered a problem with the WSS August CU.
Due to schema and stored procedure changes coming with the August CU databases with a patch level older than the August CU cannot be upgraded to August CU through database attach method.
That means that you need to be careful when upgrading your WSS or MOSS farm to August CU as the usual recommended steps to detach the content database before installing the hotfix will cause problems later when you are going to reattach the databases. In case you need to install the August CU now to resolve an issue that is covered by the fix you should avoid detaching the content databases during the hotfix installation. If the databases are attached the hotfix installation will correctly upgrade the database when running PSCONFIG.
In case you need to detach the databases it would be required to upgrade the database in a separate farm before attaching them back to the production database. E.g. install a test farm with the previous build level the databases, attach the databases there and then upgrade the test farm to August CU. Afterwards you can detach the upgraded databases from the test farm and attach them back to the production farm.
Also be aware that this will also affect database backups taken before installing August CU.
The product group is currently actively investigating this issue to identify a more elegant method to avoid this problem.
[Update: the WSS hotfix has been rereleased on October 1st. The version of the WSS August 2009 CU availble now does no longer have this problem.]