Brit prices, plus I've moved a couple from the unavailable list onto the available on EU SEN/PSN list:
1. RECOMMENDED, SONY-APPROVED FULL VITA COMPATIBILITY TITLES
The 3rd Birthday $19.99/€19,99/£15.99
Cladun: This is an RPG/Cladun X2 $19.99/€19,99/£15.99 (Cladun: This is an RPG is $9.99 on Gamestop.com, Cladun X2 is still $19.99)
Corpse Party $19.99/€14,99/£11.99
Disgaea: Afternoon of Darkness $14.99/€14,99/£9.99 ($9.99 on Gamestop.com)
Disgaea 2: Dark Hero Days $19.99/€19,99/£15.99 ($14.99 on Gamestop.com)
Dissidia 012[duodecim] $29.99/€34,99/£19.99
Fate/Extra $24.99 (Unavailable in EU)
Final Fantasy IV Complete Collection $29.99/€34,99/$19.99
Final Fantasy Tactics: War of Lions $9.99/€9,99/£7.99
Half Minute Hero $9.99/€14,99/£11.99 (Currently €7,99/£6.49 until 14-03-2012)
Knights in the Nightmare $29.99 (Unavailable in EU)
The Legend of Heroes: Trails in the Sky $19.99/€34,99/£27.99 (Bundled with Persona 2 for £47.99)
Lunar: Silver Star Harmony $14.99/€14,99/£11.99
Monster Hunter Freedom Unite $19.99/€9,99/£7.99
Persona 2: Innocent Sin $39.99/€34,99/£27.99 (Bundled with P3P for €49,99/£39.99) (Bundled with Trails in the Sky for £47.99)
Persona 3 Portable $39.99/€34,99/£27.99 (Bundled with P2:IS for €49,99/£39.99)
Phantom Brave: The Hermuda Triangle $19.99/€19,99/£15.99 ($9.99 at Gamestop.com)
Puzzle Quest: Challenge of the Warlords $9.99/£4.79
Riviera: The Promised Land $14.99/€17,99/£13.99
Tactics Ogre: Let Us Cling Together $19.99/€19,99/£15.99
Wild Arms XF $9.99/€17,99/£13.99
Yggdra Union $14.99 (Unavailable in EU)
Ys SEVEN $14.99/€14,99/£11.99
Ys: The Oath in Felghana $14.99/€14,99/£11.99
Z.H.P. $29.99/€29,99/£23.99 ($19.99 at Gamestop.com)
COMPATIBLE, BUT NOT LISTED BY SONY
Hexyz Force $29.99 (Unavailable in EU)
Jeanne d’Arc $22.99 (Unavailable in EU)
Valkyria Chronicles II Bundle with DLC: $22.49 Unbundled: €34,99/£27.99 (DLC costs €4,99/£3.99)
UNTESTED OR GAMES WHICH ARE NOT QUITE WORKING
God Eater Burst $19.99/€29,99/£23.99 (free DLC)
Gurumin: A Monstrous Adventure $14.99 (Unavailable in EU)
Patapon 3 $19.99/€26,99/£16.99
R-Type Command $14.99 (Unavailable in EU)
Untold Legends: The Warrior’s Code $14.99 (Unavailable in EU)
Ys I & II Chronicles $14.99/€19,99/£15.99
4. GAMES ONLY AVAILABLE ON EU/UK STORES
Breath of Fire III €9.99/£7.99
Final Fantasy Anniversary Edition €9.99/£7.99
Final Fantasy II Anniversary Edition €9.99/£7.99
Phantasy Star Portable 2 €34.99/£19.99
Astonishia Story (£7.99)
Spectral Souls: Resurrection of the Ethereal Empires (£13.99)
6. AVAILABLE 2nd TIER RPGS
Adventures to Go! $14.99 (Unavailable in EU)
Aedis Eclipse: Generation of Chaos $7.99/£13.99 ($5.99 at Gamestop.com)
Blade Dancer: Lineage of Light $7.99 ($5.99 at Gamestop.com) (Unavailable in EU)
Blazing Souls Accelate $34.99 (Unavailable in EU)
Class of Heroes $39.99 (Unavailable in EU)
Crimson Gem Saga $29.99 (Unavailable in EU)
Dragoneer's Aria $9.99/£11.99 ($7.99 at Gamestop.com)
Dungeon Explorer: Warriors of the Ancient Arts $11.99/£8.79
Dungeon Maker: Hunting Ground $9.99 (Unavailable in EU)
The Eye of Judgment: Legends $29.99/£19.99
Harvest Moon: Boy & Girl $14.99 (Unavailable in EU)
Harvest Moon: Hero of Leaf Valley $29.99/€29.99/£23.99 (Currently £11.99 until 14-03-2012)
Innocent Life: A Futuristic Harvest Moon $14.99/€12.99/£9.99 (Currently £5.19 until 14-03-2012)
Jikandia: The Timeless Land $24.99 (Unavailable in EU)
Justice League Heroes $9.99 (Unavailable in EU)
Kenka Bancho: Badass Rumble $39.99 (Unavailable in EU)
Kingdom of Paradise $16.99 (Unavailable in EU)
Lord of Arcana $19.99/£15.99
Mana Khemia: Student Alliance $9.99/£11.99 ($7.99 at Gamestop.com)
Mimana Iyar Chronicle $34.99 (Unavailable in EU)
Shin Megami Tensei: Persona $39.99/£19.99 (Currently £9.99 until 29-02-2012)
Untold Legends: Brotherhood of the Blade $14.99 (Unavailable in EU)
Valhalla Knights $4.99/£9.99 (Currently £5.19 until 14-03-2012)
Valhalla Knights 2: Battle Stance $9.99/£11.99 (Currently £6.49 until 14-03-2012)
Warriors of the Lost Empire $5.99 (Unavailable in EU)
7. NOT AVAILABLE AT ALL ON SEN/PSN
Brave Story: New Traveler (XSEED Games)
Crisis Core: Final Fantasy VII (Square Enix)
Dungeon Maker II: The Hidden War (UFO Interactive)
Dungeon Siege: Throne of Agony (2K Games)
Kingdom Hearts: Birth by Sleep (Square Enix)
The Legend of Heroes: A Tear of Vermillion (Namco Bandai)
The Legend of Heroes II: Prophecy of the Moonlight Witch (Namco Bandai)
The Legend of Heroes III: Song of the Ocean (Namco Bandai)
Marvel: Ultimate Alliance (Activision)
Marvel: Ultimate Alliance 2 (Activision)
Metal Gear Ac!d (Konami)
Metal Gear Ac!d 2 (Konami)
Monster Kingdom: Jewel Summoner (Atlus)
PoPoLoCrois (SCEA)
Star Ocean: First Departure (Square Enix)
Star Ocean: Second Evolution (Square Enix)
Star Ocean(Namco Bandai)
Tales of the World: Radiant Mythology (Namco Bandai)
Valkyrie Profile: Lenneth (Square Enix)
X-Men Legends II: Rise of Apocalypse (Activision)
Ys: The Ark of Napishtim (Konami)