EDIT: I did solve the problem of missing files in /var/lib/mysql/opengoo after looking at the install log, "wget" didn't get installed. Once installed I ended up with .frm, .MYI, and .MYD files BUT the install is still not complete and wants to walk me through the install process so something is still wonky.
Sorry for bringing up an old-ish thread, but I'm having this very same problem.
I installed Fedora 12 using the LiveCD (Install to HardDrive), then installed Amahi so everything was fresh.
Installing Horde does put the DB into /var/lib/mysql but I still get the message saying setup isn't complete.
Now, I wish this was the only problem.

I suppose I could re-install everything from scratch, but man...that's time consuming on the box I'm using to test Amahi out.
I suppose I could just remove the RPMs and start fresh, maybe I'll have better luck. The weird thing is some apps work fine. I installed "opendb" and it worked like a charm. Weird!
When I look at /var/lib/mysql/opengoo, this is the only file:
[root@amahi mysql]# ls opengoo/
db.opt
As for horde, all the data files are zero-length!
[root@amahi mysql]# du -chs horde/*.MYD
0 horde/horde_alarms.MYD
0 horde/horde_cache.MYD
0 horde/horde_datatree_attributes.MYD
0 horde/horde_datatree.MYD
0 horde/horde_groups_members.MYD
0 horde/horde_groups.MYD
0 horde/horde_histories.MYD
0 horde/horde_locks.MYD
0 horde/horde_perms.MYD
0 horde/horde_prefs.MYD
0 horde/horde_signups.MYD
0 horde/horde_syncml_anchors.MYD
0 horde/horde_syncml_map.MYD
0 horde/horde_tokens.MYD
0 horde/horde_users.MYD
0 horde/horde_vfs.MYD
0 horde/kronolith_events.MYD
0 horde/kronolith_shares_groups.MYD
0 horde/kronolith_shares.MYD
0 horde/kronolith_shares_users.MYD
0 horde/kronolith_storage.MYD
0 horde/mnemo_memos.MYD
0 horde/mnemo_shares_groups.MYD
0 horde/mnemo_shares.MYD
0 horde/mnemo_shares_users.MYD
0 horde/nag_shares_groups.MYD
0 horde/nag_shares.MYD
0 horde/nag_shares_users.MYD
0 horde/nag_tasks.MYD
0 horde/turba_objects.MYD
0 horde/turba_shares_groups.MYD
0 horde/turba_shares.MYD
0 horde/turba_shares_users.MYD
0 total
What in the world...?!