Well, I only heard a first rumour of this yesterday, but it's true as beans. Google have today launched their own instant messenger service, Google Talk. Featuring both text and voice chat, Google Talk is unsurprisingly only a Beta release today, but is still filled with the usual Google sexy and simpleness! No webcam support at the moment unfortunately, but I'm sure it'll be there before long.
If you have Windows XP or 2000, go on, give it a try now!