[nullc]

In the immortal words of Timecube: "You have been educated stupid".

Fortunately, salvation is readily at hand: http://www.2uo.de/myths-about-urandom/

[derekcollison]

I think entropy, in however you measure it, does influence something like a UUID generator differently than the cryptographic algorithms. What you are trying to achieve, or more importantly the condition you are trying to avoid, is different.