I've been waiting for this for the past few months. I've been number-crunching during January to March using version2.15, and I was hesitant to download v2.16, because I knew for a fact that v3.0 is due for release this year. I had difficulty using certain packages, such as randomForest, because they won't work on v2.15.
So here now my patience has paid off, and such a great timing this was: school year's almost over, and I can install the software and upgrade packages to my heart's content. I have all the time that I need.
Professor Peter Dalgaard of the Copenhagen Business School precisely wrote, in behalf of the R core team, in his letter to the community mailing list saying that R v3.0.0 is not so much about adding a lot of new features from v2.0 iterations, but rather it was decided that the codebase has "developed to a new level of maturity" that warrants a major release.
Version 3.0.0, as of this writing, contains only really major new feature: The inclusion of long vectors... More changes are likely to make it into the final release, but the main reason for having it as a new major release is that R over the last 8.5 years has reached a new level: we now have 64 bit support on all platforms, support for parallel processing, the Matrix package, and much more.Thank you R core team! Happy data crunching.