>...'day-oh' if you will.

Daylight come and me wanna go home. Oh, somebody had to say it!!!

In my cursory but immersed exposure to Asian languages, I'd tend to believe that it has something to do with all the tonal vowels ~ dipthongs that are impossible to spell with English's inadequate septumvirate. [Ooh! Look at me, I made a new word! emoticon]

As for the "t"/"d" thing, I'm ready to guess it's the Chinese equivalent of the Japanese "l"/"r" pronunciation issue. A hard "t" is roughly the same as a "d" within the spoken language.

And just this summer, I had the pleasure of visiting Beijing (see picture on Max's myspace.com account). They still call it Peking. I'm not sure why.