Since the upgrade to 3.2.2 (Build: 5859EX) I cannot make a conference call.
I can make the first call successfully, then flash to get a second dial tone, then dial the second party which I can talk to successfully.
When I do the second flash to put everyone together, I loose both parties and just get a whooshing sound similar to an FM receiver tuned between the channels.
Perhaps http://www.obitalk.com/forum/index.php?topic=13935.0 is relevant though, if another manifestation of the same problem, that thread it will give you little comfort except the post from SteveInWA saying that it was being investigated 3 weeks ago.