[Zope] What's the difference between 2.8.x and 2.9.x?

Dear all after the annoucement of Zope 2.8.7 and 2.10.0.B1, I'm a bit confused about the difference between the 2.8 and 2.9 lines? Is it mainly Python 2.4 support? Thank you, and best regards, Martin Gfeller