While I think I would prefer the interface that those games were designed for, I whole-hearted applaud you for considering this "challenge". It sounds quite interesting indeed, and I would be very interested to hear of how it goes, including the positives and the negatives of playing it on such a device. ^_^

No, touch screen works for stuff I won't consider worth of being defined "gaming" anytime soon.

In GemRB, the interface is actually unchanged. It's the good ol' Baldur's Gate interface, with the characters on one side, the screen selection buttons on the other side, and the log/hotbar at the bottom. Instead of clicking on a button, you push it with the stylus. Keyboard shortcuts can also be used, if the phone has a keyboard of course.
At least, that's how it works on Maemo. On Android, I don't know.

It's funny, because I consider Angry Birds to be Castles on steroids. Seriously, if the Castles developers could have run the complex physics calculations they run in Angry Birds, they would have.

I don't know when you started gaming, but for me it was arcades and the C64, some on the Apple IIe. When I look at some of the old games I used to play (you can pick them up on compilation "classics" discs to this day) that was indeed some simple stuff, at times.

Now, if you want to be snobbish and say most of the stuff on phones is lightweight and casual, sure I'd agree with you. I do think you're wrong about dismissing the entire platform, though. That doesn't mean you have to ever play a single game on a phone, but the fact remains that there are some pretty deep games released on phones as well. As with anything with such a low barrier to entry, there is likely to be a much higher proportion of crap, as well.

Planescape: Torment and Icewind Dale 2 are the most unusual variations of the engine, the former due to an insane amount of hardcoded hacks and the latter (partially) due to the different ruleset (and accompanying hacks). Support for both is increasing almost with each day, buth neither is completable yet. The other games should work pretty well (bugs still exist, of course, but the games are completable).

The Infinity Engine games are mostly point-and-click and render themselves quite well to touch-screen controls. Their most inhibiting feature is that they're made for higher resolutions at larger screens, so it might be a tad hard to see small details and text, both of which could be alleviated with mods (other games made for the same engine could potentially use different interfaces for different resolutions).

Thanks for these details.
The resolution problem should solve itself naturally in a matter of months as the screen resolution on phones keep increasing. On the N900, the screen resolution of 800*480 is already more than enough to run BG2 in 640*480.
The screen size is much more of a problem. That is why I prefer playing the IE games on a netbook, it's far less tiring for the eyes. But even for this use, the GemRB engine will prove extremely usefull when it's fully operationnal : think ARM-based netbooks, multi-OS support, etc...

Yes, many devices have high enough resolution, but even then it might be difficult noticing details just a few pixels large such as variations between similar letters and digits. Font mods already exists and GemRB supports scaling the UI (or was it the whole game, I don't remember) down on lower-resolution devices, a complete small-screen UI overhaul needs a lot more work to do (not to mention getting it right enough for a "seamless" drop-in) and I don't know of such a project yet.

No wonder you're sour, I would be with Windows phone. But honestly, liked you it or not, hand held devices all ready are a huge part in gaming. The fact, that you control the game with touch screen does not make a game less a game.

Gaming has changed a lot since it became mainstream, especially during the last decade. Now days all kinds of motion controllers are a norm in the industry, Nintendo has even had touch screen controlled handheld device for years, so I really don't see what your issue is other than snobbery or trolling.