Oh, I might have to have a look at how you did the tax in the development version as well. I also needed a more complex way of defining shipping. Different product types have different amounts and setups for shipping, so I actually took the tablerate module that was contributed and extended it so a table rate can be entered for each type of product, and so country, zone and postcode can have different amounts. It is quite annoying though because if you need to define different rates for many different areas, plus each different product type, it is easy to make a mistake, and also very time consuming.
So basically you can enter the following:

country_code|zone_code|postcode 1:4,4:8,8:10

Or, if you leave out country_code, zone_code and postcode, it is just the default version that is used if there isn't a match in the specific ones. Unfortunately you have to know the codes of the country and zone, so like Australia is 36, and one of the zones is 86...something like that. I was going to make it more user friendly later, but I just think the whole thing is too complex to begin with and should have a full user friendly way of entering shipping stuff.

I also thought of copying the way the tax module works for shipping, but I just didn't have the time to work on the frontend bit for my project. I'm hoping that after this big project is over, I'll be able to turn a handful of solutions I worked on into general solutions and be able to give them to the community. I'd be interested in helping in this shipping solution you have put together by copying the tax module if you like, because like I said, I had the same thought.