I think the results of your script can be more interesting if you use icmp instead of http. An http request may take different interval on the same site ( forking/pre-forking ... overloaded database ).
What do think about it ?


More Details:

Why have you chosen http to test connectivity ?
Icmp was made for that !!
the results of a ping or a traceroute may be more sharp and regular.
There's some perl module to handle it. Like this one.
I think you should also use direct ip adresse to avoid strange results due to a slow dns server.

That's all monks :)