This is a more significant announcement than any number of Fujis, Canons or whatever.
I've been playing with this all day now and it is a great upgrade. LR4 retains much of LR 3 - all that you have learned will not need to be relearned - but adds some excellent new features. Video and mapping is of no interest to me but will be a boon for those who are into those features. For those who print seriously, the soft proofing feature looks both comprehensive and easy to use.
The changes in the develop module are also for the better: more options in the graduated filter and adjustment brush and, three cheers and more, they have finally got rid of the exposure/brightness/fill light mess and come up with a more rational and sensible approach. According to M Reichmann in his introductory video, quoting from an Adobe engineer, the new approach in the Basic panel is designed to reflect some underlying changes in how LR handles files. As noted the Tone Curve panel can now apply changes on individual RGB channels - great change.
The other big new feature for me is the ability to design books (in partnership with blurb) from within LR.
Andy, this will not be a free upgrade. If you already have LR 3 my guess is you'll pay $100 for this. If you are buying from scratch $300. However, bearing in mind that much of the discussion on these forums in recent days has concerned $1500 cameras and $600 lenses, LR is a bargain.
The
Reichmann video is definitely worth a look if you are at all interested in this.