ray,
yup, hoklo (although i usually call it taiwanese, a more direct translation of "tai-yu").
people in southern and central taiwan (especially the rural areas) speak taiwanese. this is especially true of the older population, whose usual order of language-learning was Japanese, Taiwanese, and
then Mandarin.
however, most people these days view taiwanese as something of an informal language, to be used around friends and family. mandarin is used for most events, especially formal ones. interestingly enough, many of the young people in taiwan have only a limited knowledge of taiwanese, as for a while the use of taiwanese was looked down upon (it used to be banned under chiang kai-shek). however, having said that, the vast majority of the people in taiwan have a working knowledge of taiwanese.
these days, taiwanese is gaining something of a "cool" factor again, and thus radio stations and TV shows will inevitably throw in a few phrases of taiwanese here or there- just as they used to do (and still do) with english.
a tad inconvenient for me, someone who understands taiwanese but speaks it with a horrible accent! if i go down south, and order food, or hail a taxi-cab in mandarin, i get more and more funny looks!
