This doesn't appear to be advertised at the moment (Free on $49 is being promoted), but it's the cheapest, decent (ie not slow and with a reasonably up to date OS) Android handset that I can see on the market at anything below $40/month.
Add to that the current 3 months free offer by applying the "dancehall" code and possibly a $100 credit (although I can't work out how to apply that) for new customers* and it's an even better deal.
Works out to $819 total ($34.13/month) over the life of the contract (or $719 - $29.96/month if you can score the extra $100 Credit)
I'm a current customer nearing the end of contract in the next week.
My plan is to flip back to Prepaid at the conclusion of my contract and then sign up on this (assuming it's still available) to try to get the $100 Credit as well.
In the past, I've been credited with "new customer" deals with Virginmobile when I have used this method.
*NOTE: The $100 Joining Credit is reportedly not applicable to the $39Cap offer.. despite the fact it is listed on the Virgin website here:
http://www.virginmobile.com.au/Shop/Rate-Plan-Details/8390/E…
Used both side by side, Galaxy wins flawlessy.
Polished UI, lag free animations (Nexus suffers a bit of jitter even without many apps installed) and smaller resolution.
Unsure if 2.2 of Nexus One has SWYPE, which is also worth noting.