There have been some important upgrades to Agile Messenger [iTunes Link] since I last wrote about the multi-client chat app. Notably: a "walk and talk" feature that uses an iPhone camera to give you a view in front of your phone if you want to chat and walk at the same time. That's useful if you're going to type and walk around, but the under-the-hood upgrades are worth a mention as well. The biggest update for me was the ability to search contacts. If you have dozens of contacts, being able to search by name is essential; scrolling a huge set of lists is a chore. Searching works great in Agile Messenger, I'm happy to report. Push notifications work exactly as they did before.
There are some cosmetic tweaks and performance tweaks, and I noticed the performance seemed snappier overall. Still, BeeJive recently added (somewhat limited) chat room support, which Agile still lacks. The iPhone IM wars are still on!
Agile Messenger is only $1.99 for the next couple of weeks, which is a steal for the normally $9.99 app. If you use IM a lot, it's a great experience.