Title pretty much says it all. The latest version of iOS for iPod Touch, iPhone and iPad will be released today, and it will be including a free version of 'Find My iPhone', previously only available as part of the $99/year Mobile Me. They of course waited until my account just renewed before releasing this of course, because find my iPhone is one of the only 2 reasons that I pay the Apple Tax for this service.
If you don't know what's coming in 4.2, well, google is your friend here, search it. Course, the short answer is feature parity for iPad with iPhone, plus a few minor little things. The press release with details is here (thanks @johnkoetsier).