I have successfully connected a 40x2 LCD to my Arduino and got it displaying a message:http://www.flickr.com/photos/anachrocomputer/3216168181/
Things start going a bit peculiar, though, when I unplug the LCD (with the power off!) and plug in a 16x1 LCD. The text appears as just a row of junk characters, and sometimes changes when I reset the Arduino (which makes the sketch re-send the data). I'm using the official LiquidCrystal library in 4-bit mode.
Now, the smaller LCD has a genuine Hitachi HD44780 chip on it, while the big one is a clone. In the code for the library, I see that there are no time delays between the calls to digitalWrite that set the Enable pin high and then low. I'm going to try a few things in there, and see if I can fix it.
Has anyone else seen troubles with LCDs that have a genuine HD44780 chip?