Release notes? New features? Er, nope - Eclipse.org is a case study in how making software into abstract 'products and platforms' has the potential to make it so vague that you could be, in fact, downloading anything at all, which constitutes a subproject of the Eclipse project platform, which I assume is a hamburger.
I will admit it would be nice to have a single list of "release notes" but there are like 30 various projects and some 20+ million lines of code getting released all at once. Keep track of all of that at once, let alone at detail fine enough to be useful would be difficult.
As a result they have been doing a "blogathon" where various community members are posting whats new, etc. On the main page of eclipse.org I clicked on blogathon.
On the page that comes up (http://eclipse.org/helios/blogathon/reviews.php):
Eclipse Helios: What’s New in JDT
Top 10 Eclipse Helios Features
Let’s See What’s New in Eclipse 3.6
Git Support, Top Eclipse Helios Feature #2
New and noteworthy in Helios (Eclipse 3.6)
etc, etc etc.