There is a possible error when using the automated upgrade tool to upgrade to WordPress 2.8.
If you get far enough in the upgrade process that the archive has been downloaded from WordPress and extracted and then hit an error (like bad permissions) WordPress is supposed to delete the new files. Instead it appears that it deletes all the files rendering your blog unusable.
Should BuyHTTP Customers Worry?
Thanks to our fully managed ownership/permissions system you should not run into this issue. Upgrading our blog using the automated tool could not have been easier. If you do run into this issue, thanks to BuyHTTP Data Vault you can restore all of your files in a matter of a few minutes and be back up and running. Then you can run a manual upgrade.
Follow this bug: Trac ticket # 10140
Found via WPEngineer.