i have noticed now on cs5 that the options for interactive pdf have changed,i remember i had the option in the fly out menu to hide button show button in pdf
and other various options,if it was printable etc etc.But now the only option available is printable button,and i assume i can type a description in the dialgoue box.
the previous versions had a much richer options.
I presume you are referring to changes from CS4.
I don't do the interactive stuff in my work, but with CS5 PDF export was devided into two flavors, Interactive or Print, and I think that accounts for the difference you are seeing. Buttons don't actually work in PDF(Print) exported from CS5, but you have the option of having them visible.