Apple just went live with an update to iOS 4 that it says “Improves the formula to determine how many bars of signal to display.” The update, which comes in the form 4.0.1, arrives just ahead of a planned press conference tomorrow, in which most believe Apple will address the ongoing drama surrounding the iPhone 4’s antenna.

While many believe the iPhone 4’s antenna problem is a design flaw and purely hardware based, Apple insisted in a July 2 open letter that the problem could be the result of a software glitch.

“Upon investigation, we were stunned to find that the formula we use to calculate how many bars of signal strength to display is totally wrong,” read the letter. “Our formula, in many instances, mistakenly displays 2 more bars than it should for a given signal strength.”

The letter goes on to claim that users who observe a drop of several bars “when they grip their iPhone in a certain way” are most likely in an area with very weak signal strength, but they don’t know it because “we are erroneously displaying 4 or 5 bars.”

“Their big drop in bars is because their high bars were never real in the first place,” Apple claims.

Just this week, Consumer Reports said it could not recommend the iPhone 4 because of its antenna issues, but still managed to give the iPhone 4 the highest rating of any smartphone on the market.

Regardless of the ongoing issue with its antenna, the iPhone 4 has sold well. According to Apple, more than 1.7 million units of the phone sold in its first three days on the market.