Existing Itemization Overhaul

We know that existing items are being converted to the new itemization rules, but what can you personally expect?

Let's compare a few hallmark items. I'll be touching on a trinket, a weapon, and a couple random cloth pieces here, comparing their current stats to their Cataclysm stats.

First up is a weapon, the Frozen Bonespike (normal).
Current stats:
67 Stamina
67 Intellect
59 Spirit
59 Crit
741 Spellpower

Cataclysm stats:
126 Stamina (+59)
0 Intellect (Weapons seem to have spellpower only, rather than intellect only)
59 Spirit (unchanged)
59 Crit (unchanged)
928 Spellpower (+187, 67 of which can be presumed to have come from intellect)

Trinkets
Not going to go over trinkets in detail, only mention that Phylactery, DFO, Sundial, NMIC, and the other prominent caster trinkets didn't change. They still proc spellpower, likely to prevent wild up and down swings in mana pool sizes.

Cloth: Heroic Sanctified Dark Coven Robe
Current stats:
139 Stamina
139 Intellect
Red/Yellow sockets, +7 SP bonus
122 Crit
106 Haste
195 Spellpower

Cataclysm Stats:
261 Stamina (+122)
167 intellect (+28)
Red/Yellow sockets, +7 SP bonus
122 Crit
106 Haste
0 Spellpower (167 from intellect, a reduction of 28)

So, over your entire set, what can you expect?
Lots and lots of stamina - Expect almost doubled stamina the day you log into patch 4.0. The slack itemization of dropping every caster epic from 5 stats to 4 mostly went into stamina. Unlike the BC stamina inflation, you won't have to regear for this one, your health is skyrocketed right out of the box.
Similar spellpower - Weapons went up quite a bit, but armor generally went down. Looks like average at equal item level might be a wash, which has been a stated intention anyway. Your results will vary - if your weapon is notably higher or lower itemlevel than the bulk of your armor, you'll see more significant gain or loss.
Slightly larger mana pools - Weapons dropped intellect, but everything else gained a good chunk.
Identical ratings - Crit, haste, spirit, and hit didn't go anywhere on any items I looked at.

Most importantly, Expect all bets off the second you ding 81. Cataclysm blues are redonkulous. Yes, I said redonkulous, because ridiculous isn't a big enough word. Shadowmourne won't last to 85, let alone whatever piece of shit gear you're wearing. Remember the last two expansions, where people said "Whaa whaa my epics are replaced by greens in two levels" but in reality good high tier epics lasted until the new endgame? Well, now the whaaaambulance finally arrived for real. Itemlevels take off fast. Expect six digit health, mana pools big enough that 72k mana water you can get at 85 is just as annoying as the 19.2k stuff is now. If you like numbers and like feeling your character get truely powerful, Cataclysm looks like it might just be YOUR expansion.