If you are already using Trillian on your Windows-based PC, you’ll be ecstatic to learn that the multi-protocol instant messaging program has finally dropped an iPhone version into the iTunes App Store. If you aren’t familiar, Trillian allows users to connect to multiple messaging services or accounts, including AIM, ICQ, Yahoo!, Windows Live Messenger, Jabber, MySpaceIM and Google Talk.

If you haven’t used Trillian before, you’ll need to register for a Trillian Astra account. As it has been years since I’ve been a PC user (Trillian isn’t available for Mac OS) I needed to sign up for an account, but I did so in-app, and the confirmation email was designed to be accessed via iPhone, making the process easy. Once you’ve setup all your connections (this will sync automatically if you already use Trillian) you’re ready to chat. Trillian offers fast push notifications of incoming messages, so you don’t have to keep the app running at all times. Launching the app is a little slow on my 3G, but the speed isn’t an app killer. Users can only stay logged into Trillian for 24 hours, something that the developers plan to increase in future updates. There is no landscape mode in this version, but that is also in development.

Unlike desktop Trillian, there is no support for Twitter or Facebook messaging in iPhone Trillian. I would have rather seen Facebook support in this version than MySpaceIM (seriously, are people still using MySpace?) so I hope to see this implemented in a future version.