A few problems:

• Your extensions don't match just the end of the file name.
• You're missing a '=>' after the second 'name'.
• The pruning rule doesn't seem to work in combination with the first 'file => name' rule (update: if the 'file => name' rule comes after the 'not ( ... prune )' rule), then the procedural answer works).
• The dirs still are not right. you shouldn't have a leading slash, and you probably ought to anchor the regex.

I couldn't get the prune to work with the procedural interface, so here's the OO style answer:

#!/usr/bin/perl

use strict;
use warnings;

use File::Find::Rule;
use constant FFR => "File::Find::Rule";

my $ext = qr/\.(?:html|php)$/;
my $dirs = qr/^(?:cgi-bin|log)$/;
my $base = "c:/blub";

my @files = FFR->or(
  FFR->directory->name($dirs)->prune->discard,
  FFR->file->name($ext),
)->in($base);
print "$_\n" for @files;
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Update: The procedural interface works if you put the first 'file => name ...' rule AFTER the 'not ... => prune' rule (just like it is above in the OO interface).