It only took them an extra two months from their projected date, but developer Petroglyph finally got Patch 3 for Universe at War approved and applied by Microsoft. They had one previous attempt, but for whatever reason, it was denied.

Anyone who's kept up with this game knows it was supposed to have cross-platform play (including achievements tied to that), but up until yesterday it wasn't possible.  In addition, many achievements on both the 360 and the PC version were glitched and now fixed, though it appears they may have missed one glitch on the 360 version ("Nothing to See Here"). Another big change is the removal of the possibility for "co-op" play over the platforms. One achievement used to be called "Forged Alliance" for playing on a team with a cross-platform player. That has been removed and replaced by an achievement called "Peacebringer" for beating two cross-platform opponents. There was already an achievement for beating five cross-platform opponents, so that wasn't very inventive.

At any rate, the full 1000 is now possible (at least on the PC version which I completed last night), so check out all the patch notes at the Petroglyph forums for some of the actual gameplay changes.