Cerulean Studios has begun beta testing Trillian for the iPhone, and BigBlueBall has new screenshots.
The closed beta began tonight, and requires the iPhone OS 3.0. I've been running this Trillian beta on my year-old iPhone 3G for less than an hour, and I'm already impressed.
Trillian for iPhone allows you to swipe to switch between open chats. Like the Trillian Astra web client which is now in public beta testing, this retains the groups you have already setup for your Trillian account and keeps them in sync.
Of course, it supports push notification so you can appear signed in even after you close the app (it's configurable) and receive incoming instant messages. If you want to reply, it automatically launches Trillian and restores your chats.
Trillian for iPhone integrates with your iPhone camera, allowing you to take and send photos to your contacts, or to use it to create a new avatar or buddy icon.
Currently, there is no file transfer capability (other than for photos) and emoticons appear as plain text.
Being a beta, it's still a little buggy. I tried sending a second photo and it crashed on me. Starting it back up I tried again, and it went through just fine.
Cerulean Studios has left the door open to add a few small enhancements before the launch this (apart from fixing any bugs found).
If you're interested in signing up for the Trillian for iPhone beta, you can learn more here. They currently aren't accepting any new testers, but that will change as they get closer to launch.
If you already use Trillian and have an iPhone, this could be an IM worth getting… when it becomes available. There is no word yet on when it will be ready for submittal to the iPhone App directory, or what the pricing will be.