Google talk is very similar to yahoo messenger, or AOL’s AIM thing, and Microsoft’s messenger – if you are using a windows based PC.
If you are on a Mac you can still use google talk through your gmail account for video chatting with other people. If you have a PC, you can enable the google talk to work similar to the other messenger IM services from your desktop to chat, share files, etc.
To learn more about google talk, or to download the google talk software for a PC – find more about google talk here.
Google talk is a good option if you have a core group of friends or business associates that are all using gmail, or google’s Orkut social network. There have been many privacy issues raised about google in general, so it will be interesting to see if many people jump on board to use this google service, or if the people who have been experimenting will jump off this ship and choose to use something that is more universal and something that has more privacy built in like Skype.