I’m not really sure which iPhone view you’re referring to – if it’s the “Forecast” view, then OmniFocus 2.x has that in place already, and it should more or less work the same way.
However, what you seem to be asking for goes beyond that. Assuming that by “available tasks for the day” you mean any task that isn’t blocked or deferred, then you should be able to setup a Perspective like the following:
This inherently includes “Due” tasks, as those are obviously "available’ but with the “Sort” option, they’ll be filtered to the top of the list.
If you’re looking to do this for days other than today, then that’s considerably more complicated. Perspectives aren’t based on a user-specified date – they always reflect what’s available in the here and now. The Forecast view offers the ability to see what’s due on a certain day, as well as what’s starting on that day (if you’ve set it to do so), but that still won’t include tasks that just happen to be “available” because the defer date has already passed or they didn’t have one to begin with.