ICQ is closing down. It was really at its height in 2000 and that is when we integrated ICQ into Opera. We made a small (5k) client and it worked really well.
AOL had purchased ICQ and they were concerned about MSN taking users from them by connecting to their service, so they stopped supporting 3rd party clients. We contacted them, to see if they would make an exception for us, but they did not.
They said that if we removed our 5k client, we could maybe discuss bundling their client, but it was bigger than Opera, so that was not going to happen.