It looks like they've come up with a good compromise for the currency problem. Those who wish to will be able to set exact prices in the buyer's currency, while the '~' approximations will still be used for those who don't. From the email I just received from them:

We are introducing a new feature called Buyer’s Currency that lets you set prices for your apps separately in each of the currencies on Android Market. We are deploying this feature country-by-country over the next few months, starting with developers in the U.S. When the feature is available to you, we will notify you by email.