Re Burton's Penguin
The Penguin played by Danny DeVito is not the Penguin of the comics, but a stupid "Art with a capital F" creation of Tim Burton.
Batman Returns blew hairy goats in a large number of ways, not the least being turning the Penguin into some sort of unrealistic freak and psychopathic killer.
The comic-book Penguin was a perfectly sane and gentlemanly criminal mastermind and mob boss who was ragged as a kid for his beak-like nose, obesity and short stature. In one rendering he also used to also have a waddling gait as a child due to a hip deformity (which did not trouble him as an adult.) He favours the gentlmanly/aristocratic look (came from well-to-do parents) and the shortness, obesity, beaky nose and his predilection for tuxedos gets him the moniker of "the Penguin" - no deformed hands, not cast into the sewers and raised by penguins at the zoo or any of the other rubbish from Burton's crapfest.
If the Penguin were to appear in the next Batman movie, he could easily be handled as a dapper and aristocratic mob boss of the Falcone/Maroni stripe. The "Iceberg Lounge" - his private club and front for his crime organisation - was referenced in The Dark Knight viral marketing as an advert in the "Gotham Times" so they could tie it across quite easily.
Whether they will or not is a different matter. Goyer said they preferred to use characters not already given an outing in the previous films - but that was before they had the Joker and Two Face in TDK.
Frankly, the scope is there to bring Two Face back, still intent on vengeance against Batman and Gordon - I know how I would handle it and I'm pretty sure if Nolan wanted to, he's intelligent enough to have it already planned.
As to the Riddler, he could make an interesting villain if done right. I rather doubt there would be the stupid mind-reading machine crap a la Schumacher. If they Get Depp to play it he'd do a brilliant job. David Tennant has apparently also expressed an interest in the role.
Catwoman would have to be portrayed as a cat-burglar if at all - the "cat-costumed vigilante hunting down the man who threw her out a window" version of Batman Returns is too close to being a "good guy". Batman in BR came across as "there's only enough room in this town for *one* costumed vigilante, bitch!"
If they were to bring her in, she'd have to be a seriously talented thief going after some major loot. They'd have to work hard to make her a "threat" though.
Frankly, a traditional Penguin would be a bigger threat than Catwoman - Batman's enough of a threat to "business" to warrant Cobblepot ordering his henchmen to kill Batman.
Biting the hand that feeds IT
