You can pass a function to findAll:
>>> print soupHandler.findAll('div', id=lambda x: x and x.startswith('post-'))
[<div id="post-45">...</div>, <div id="post-334">...</div>]
Or a regular expression:
>>> print soupHandler.findAll('div', id=re.compile('^post-'))
[<div id="post-45">...</div>, <div id="post-334">...</div>]