Here is a list of changes since 2.5.2420.

New packages:

dyntree
guitbeamer
guitlogo

Updated packages:

csquotes
struktex
textpos
xytree

Removed packages:

guit
m-bib

Fixed bugs:

[ 1538939 ] "Letter" paper format listed twice
[ 1542344 ] cannot change new format name from "newformat"
[ 1543688 ] Type 3 fonts in Miktex 2.5
[ 1545166 ] New Metapost assumes MPost files to have .mp extension