A Question Of Tagging

OK. So I have recently built a new tagging system for podcast.com (which is inches away from a big overhaul) and a few other sites I build, and I wanted to ask you a question:

Which would be the preferable ‘delimeter’ to post multiple tags?

Spaces (with quotes to enclose multiple words)? Eg: cat furry “my pet” “eats mice” – As seen in flickr

or

Commas : Eg: cat, furry, my pet, eats miceย  – As seen in WordPress?

I personally think commas is easier, but how about you?