Hi all you Simsters,
Here in Australia I use our "National" carrier Telstra due to it's extensive coverage for my iPhone 4.
When we bought our iPad last year we found the most inexpensive option for 3G was with VodaFone and got one of their micro-sims on a "prepaid" basis. Trouble was remembering to "top it up" before the expiry to conserve the unused (initial 1Gb) data allowance... As it wasn't in daily "outdoor use" we're without data again, and last time we looked, it's become much more expensive to recharge, with the minimum cost rising from $9.95 to $49.95!
So I've done a little test earlier today and taken my iPhone 4 Telstra microsim and popped it into the iPad: no problemo! data works fine, so basically it would follow that any data plan enabled microsim should provide "Wireless 3G" freedom.
Now I see that a certain retailer is offering a VodaFone "dongle" for $99 ("half price") with 15Gb of included download and 365 day expiry. Me thinks that this ought to work in my favour, if the "dongle" sim is not a micro I'll get a "cutter" off
eBay (~$20 shipped w/- adaptors to resize up to "sim") and simply insert modifed VF sim into iPad and have shiploads of data for the next year for peanuts.
I'll return with a report on the outcome of the "experiment"