The current release is ICQ 2000b Beta v4.60 Build #3278, released
October 25, 2000.
I have had ICQ for several years, since close to the beginning. I know from conversations with various people that originally the numbers were assigned somewhat randomly and the fact that you had a 7-digit UIN does not necessarily render you "l33t". I originally was #5701550, but since the servers were notoriously bad at the time, they never saved any of my information so that when I finally forgot my password they refused to email it to me on the grounds that they did not have my email address on file. I was a tad miffed. Currently, that number has no info at all, although it once had my Nick of the moment.
I use ICQ to communicate with people from around the world, including people I originally met through Hardwood Hearts, Hardwood Spades, The SciFiVine (originally SciFiSites), imood, here, and various other places around the internet. I also use ICQ for the purpose of exchanging pictures, exchanging mp3s, and voice messaging. It has come a long way from the program I originally downloaded so long ago and the latest release sports a revamped User's Details window and a few fixes.
One thing particularly notable in the latest version is that the plugin options have been separated from the main program. Now, when you download ICQ, you get only the basic program. If you wish to have ICQ Voice Message, ICQ Help, or ICQ Web Front, to name a few, you will have to visit the ICQ Plug-in Center at the Mirabilis site to download those. The ICQ download is currently 5.1mb.
Unfortunately, there are some odd compatibility issues when converting the user database from ICQ99 to ICQ2000 and if you are particularly unfortunate, you may lose your entire db. This happens rarely, but when upgrading you should always backup your db in case of this so that you don't have to lose everything, although what you would do with it outside of ICQ I couldn't tell you. My db had been corrupted and I was completely unable to convert it. The loss actually freed about 148mb of space on my hard drive that had been taken up with the message history of several years.
My current UIN is 22746352, and at this moment my Nick is Neko no Aijo.