Is there an easy way to normalize-space with given string functions

Hi,

i am looking for something like

$ SELECT btrim(replace(' too   many   spaces!  ', '\s+',' '), '');
too many spaces

i searched the function list and tried to combine to or more functions, but i 
miss a replace function which uses regular expressions.

Do i have to write my own function or did i miss something? trimming is well 
supported at the start and end of string, but no trimmin in the middle seems 
to be possible.

kind regards
janning