What is the best chat/IM application you have used and did it have any specific features that would be of use for development teams?
If you're planning on using IM to communicate among developers, you should look into setting up a dedicated Jabber server. There are numerous cross-platform servers to choose from depending on your needs, but Openfire seems to be both simple to set up and robust with features. With Openfire, as with most others, you can even set up chat rooms with histories that can be logged and be reviewed from chat applications.
There are also many cross-platform applications that will connect to a Jabber service. Specifically, Pidgin/GAIM on Windows and Linux works well, as does Adium on the Mac. All the software mentioned here is released under an open source license and is completely free to use.
Personally I prefer Jabber as well, but it's really to each their own. Which is why I like clients like Digsby (Windows, Mac), Trillian (Windows), CenterIM (*nix), GAIM/Pidgin (Windows, *nix, Mac), Adium (Mac) etc..
The ones I noted down are pretty much available across different OS' and they allow you to hook into any protocol - AIM, ICQ, Y!, Jabber (Gtalk, ...), Facebook, etc.. So you can talk to anyone and people can use whatever they feel like/prefer.
Lots of people I deal with lately kind of standardize on Skype. It seems to be the one thing that everybody got.
One alternative if you want an interface that is less graphically intensive or simply want to combine your IM into your favorite IRC client is to have a look at Bitlbee It is a IM<->IRC gateway application.
It does take a little bit of work to setup, but if you do then you have the option of combining it with irssi and screen which allows you to be connected to your IM account from multiple locations simultaneously Very useful if you development requires you to use multiple machines at the same time.
We use GoogleTalk, not sure if its the best, but its nice and clean and does the job.
If you are working with a team I'd suggest using IRC. IM chat is great 1-to-1, but IRC is a much better communication form for teams.
Set up a room on irc.freenode.net and get all the developers in there and use it to communicate with everyone in a group fashion. I've found that it typically unifies the team better as a cohesive social group by providing group communication and inclusion which ultimately results in better team work.
"Best" I'm not sure about, but..
- http://www.campfirenow.com/ - a web-based group-chat, which seems popular..
- Jabber, which does allow "conferences" (multi-user chat), and has many different clients. Mainly person-to-person chat
- IRC, which is easy enough to setup (for a local network, you can basically install any IRC server and use the default configs. I wouldn't worry about setting up nickserv/chanserv/etc for non-public servers). It's allows different "rooms" to be made trivially, there are many many different clients (including lots of decent command-line ones, decent GUI ones, java and web based ones etc etc), and allows private messaging. I wouldn't recommend using a public IRC channel for your internal messaging.
- Skype, the most ubiquitous voice-chat application, available on Windows/OS X/Linux, works very well, no server requires setting up. I would recommend using a different method for regular messaging (say, jabber or IRC), and use Skype for voice-chat.
I was using 3 IM clients: QIP for ICQ Yahoo Messenger to contact with customers in Yahoo MSN Messenger to contact with customers in MSN
then i've found Pidgin it's awsome IM client, it allows me to combine all protocols above in one place. Also allows me conference feature.
I use meebo. It's browser based, and combines gtalk, msn, yahoo, and even AOL IM.
I use it over https so it's secure (on my end)
It also retains chat histories...
I use multi-protocol IM clients because people I know tend to use different IM's (such as Jabber, ICQ, MSN, Yahoo, AIM, GTalk). The only protocol I won't use them in is with IRC because of the tediousness of handling multiple servers and users at once in an IM client.
For voice-over-IP there is Skype, Ventrilo and TeamSpeak. The GTalk client also has VoIP but it only supports 1-on-1.
On Linux I use the one that follows with KDE, Kopete. For IRC I use XChat.
On Windows I've used Trillian but found it to be bloated. Instead I use Miranda-IM because it is very light-weight and supports all sorts of protocols. For IRC I use mIRC that I've used since I started to use the Internet (which was too many years ago, I don't even want to think about how old I am now).
On Mac there is Adium, and I believe it is the only multi-protocol IM client for the moment available for the mac. I haven't had the chance to use IRC on mac, but there are several of those to choose from.
If you're looking for dedicated IM for your dev team so they can work undisturbed by others, you might want to set up a Jabber server.
Skype is the easiest answer, because it provides great voice and video.
As others have stated something like trillian that provides multiple chat protocols/logins across multiple services is also nice.
But I'd also like to suggest Microsoft's Shared View. What Shared View gives you that I haven't seen in the others is the ability to chat and share an active window with up to 15 other people on a conference, and you can relinquish control of that screen to any of them - with each person with a share of the control getting their own mouse cursor.
It's made it very easy for our team to have two or three people looking over a coding window, and "taking the helm" as it were on a task.
If you are developers, then you may want to use your IM/Chat/Presence system as a programming tool. If that's the case, an XMPP-based system will be far more flexible than anything else.
We use the multi-protocol client Pidgin with the Off-the-Record Messaging plugin for encryption and perfect forward security.
For exchanging code we have an in-house copy of Pastebin.