Version 0.8.8 is now re-released on the experimental download page.
It requires and includes KeePassRPC version 0.8.9 so hopefully a standard upgrade through Firefox will do the trick but if you do have problems, please delete the KeePassRPC plugin from the KeePass plugins folder. There also may be an issue with the release candidate of Firefox 4 which means that you should wait until Firefox has started before opening KeePass to trigger the start of the upgrade procedure - I’ll investigate that more in a few days and release a fixed version if necessary.
PS: If you’re interested, the problem with the initial upload was that I forgot to include a tiny icon in the KeePassRPC.plgx package.