For those not using the PHP SDK and are hitting the relevant Graph API URL directly, simply append
&limit=SOMEPOSITIVEINTEGER
to the end of the URL like so:
https://graph.facebook.com/PAGEGRAPHOBJECTID/posts/&since=2011-07-01&until=2012-08-08&access_token=ACCESSTOKEN&limit=100
Unfortunately, depending on which Graph resource you're hitting, you may get an error if the limit is over a certain threshold and there's no rhyme or reason to this that I can ascertain. For example, getting comments or likes for a post, I've used a limit of 4900 without getting an error. When getting posts from the page feed, that same number gave me an error and now I use a limit of 100 then paginate until my cron sees posts outside the date range.
I imagine though that FB would like for us to use the default limit of 25 and paginate so I'm personally refactoring to accomodate this.