As we discovered this morning, Optus will be the first local carrier to sell the BlackBerry Torch, offering it on a range of plans from $79. The most interesting of those plans incorporates an additional USB modem for 3G wireless access — essentially tethering without actually tethering.
The standard $79 business plan includes 1GB of data for use on the Torch. For an additional $10, you get a USB 3G modem with an additional 500MB of data. While the USB has its own SIM, the data allowance is shared between the two devices. Accessing email on the Torch and using the native browser don't count against your allowance, so in practice that's 1.5GB of data for $10, which is pretty good compared to current rates
The bad news is this is a business-only bundle, so you won't be able to get it as an individual unless you already have an ABN. Hopefully it signals the beginning of a more flexible attitude towards swapping data allowances between devices (though I can't foresee any imminent merger coming with iPad plans, sadly).
Alternatively, if you just want the Torch itself, Optus will sell it outright for $869. Bear in mind though that using a BlackBerry effectively requires you to have a plan with BlackBerry Internet Service built-in — if you just plug in a standard SIM, you can make calls and browse the web, but you won't get the BlackBerry's trademark email integration, which makes buying the phone seem somewhat strange.