It was about time (with all the rumors) for Google to release an instant messenger service -
GoogleTalk.
I downloaded, installed and used it and I must say that I like it, mainly because it is very simple and it does what it is supposed to do - allows you to talk with your friends.

First of all you can use it only if you already have a Gmail account. This is invitation based so if you don't have one drop me an email to
spuby2000@gmail.com (have about 50) and I will send one.
Once you have an account you can download the
GoogleTalk setup (under 1Mb - the advantage of not being bloatware) and install it.
Of course you have to accept a license agreement and discover for yourself that once installed
GoogleTalk will update automatically (just like the Google Toolbar does) - about the only annoying thing in this agreement (really!?).
11. Automatic Updates. The Google Talk Client may communicate with Google's servers to check for available updates to the software, including bug fixes, patches, enhanced functions, missing plug-ins and new versions (collectively, "Updates"). During this process, the Client sends Google a request for the latest version information. By installing Google Talk, you hereby agree to automatically request and receive Updates from Google's servers.
If you want to use it you must accept it of course:

One thing to appreciate is the fact that they sustain open source, as you can see the installer used is
Nullsoft Install System v2.08 (site unavailable at this point).
After installation, you'll have to enter your Gmail username and password and log in:

At the first attempt, I got a "Cannot connect to server" error, so if you are using a proxy go to Settings->Connection and select "Use the following proxy" instead of "Detect proxy automatically" and enter your proxy address - this worked for me.
Just like Yahoo Messenger, once you are connected it will announce you when you receive new emails and display little from its content on a small window:

You can use the "Add friend" link (at the bottom right corner) to invite your friends - you'll need to enter their Gmail address or send them an invitation to their existing email address (if you have that in your Gmail address book).
One interesting thing, if you right click the tray icon and select "About" there is a grayed row with the text "play 23 21 13 16 21 19 . 7 1 13 5".

What does this mean? If you will use 1 = a 2 = b 3 = c ... it will translate as "play wumpus.game".
According to
Wikipedia, this is an old computer game:
There is a version of Hunt the Wumpus found in Google Talk. Add wumpus.game@gmail.com to your buddy list, allow it to add you to its buddy list, and send it a text message (anything works). Instructions will be offered if you say 'y' when it asks.
To be honest even if I invited that person nothing happened, it still shows "Invited" message - maybe is just another viral marketing thing from big G.
Anyway, after you invite your friends you'll be able to use GoogleTalk and I'm sure that this will become one of the leaders in Instant Messaging. A small description of GoogleTalk from
talk.google.com:
They say talk is cheap. Google thinks it should be free. Google Talk enables you to call or send instant messages to your friends for free–anytime, anywhere in the world. Google Talk offers you:
Choice: Get in touch over email, IM or a call
Quality: Talk through your computer but hear your friends as if they were in the same room
Convenience: Your Gmail contacts are pre-loaded into Google Talk so inviting or talking to your friends is just a click away
Google Talk is in beta and requires a Gmail username and password.
Don't have Gmail? Get an account using your mobile phone (US only).

[update]
When you send an invitation to a person via
GoogleTalk, this is what they get in the email:
I've been using Google Talk and thought you might like to try it out.
We can use it to call each other for free over the internet. Here's an invitation to download Google Talk. Give it a try!
-----------------------------------------------------------------------
Claudiu Spulber has invited you to sign up for Google Talk so you can talk to each other for free over your computers.
To go to the Google Talk download page, visit: http://mail.google.com/mail/talk/download
Google Talk is a downloadable Windows application that offers:
- Free calls over your computer anytime, from anywhere, and for as long as you want
- A simple and intuitive user interface for sending instant messages or making calls - no clutter, pop-ups or ads
- Superior voice quality through just a microphone and computer speaker
- A shared Gmail contacts list that updates automatically with the people you communicate with most often
Once you download Google Talk, just sign in with your Gmail username and password. You can then begin inviting anyone you want to talk to for free. Google Talk lets you email your contacts directly using Gmail and you can even receive new Gmail message notifications.
Google Talk works with any computer speaker and microphone, such as the ones built-in to many PC laptops today, as well as with wired and wireless headsets and USB phones. Google Talk also works across all firewalls.
Google Talk is still in beta. Just like with Gmail, we're working hard to add features and make improvements, so we might also ask for your comments and suggestions periodically. We appreciate your help in making it even better!
Thanks,
The Google Talk Team
To learn more about Google Talk before signing up, visit:
http://www.google.com/talk/about.html
(If clicking the URLs in this message does not work, copy and paste
them into the address bar of your browser).
Other links:
Google Talk - official websiteGoogleTalk - Terms of UseGoogle Talk's very first secretsGoogle Talk - Third Party Applications