Apple released its expected update for its iconic iPhone yesterday, fixing several critical bugs and adding news features, such as the ability to buy tracks from the iTunes music store over a Wi-Fi connection.

What many users want to know, however, is whether the Version 1.1.1 update "bricks" modified phones, particularly those that have been unlocked using one of the several hacks circulating on the Internet. As of mid-afternoon Thursday, initial reports are that the update causes problems for unlocked iPhones, but it does not leave them completely unusable.

Among the more prosaic parts of the 152MB Software Update Version 1.1.1 are the iTunes Wi-Fi Music Store, a fix for the low speakerphone and receiver volume problem many users have reported, and the new ability to view email attachments in both portrait and landscape mode. Also included in the update are patches for 10 vulnerabilities, seven of which involve the iPhone's built-in Safari browser. Several of the Safari flaws are cross-site scripting vulnerabilities.

Before the update installs, however, it displays a security message - the first time Apple has done this on iPhone upgrades - that essentially repeats the warning the company issued Monday: that modifying the device voids its warranty and may leave it incapacitated.

"WARNING: Apple has discovered that some of the unauthorized unlocking programs available on the Internet may cause irreparable damage to the iPhone's software," the message read. "If you have modified your iPhone's software, applying this software update may result in your iPhone becoming permanently inoperable."

Initial reports of 1.1.1's impact on modified or unlocked iPhones were sketchy as of 3 p.m. EDT. Some users claimed that the update broke all unauthorized, third-party applications added to iPhones using the popular Others reported that unlocked iPhones returned SIM errors after the update, requiring that they restore the phone to its out-of-box state.

Several owners of unlocked iPhones, however, said that they were able to restore the devices after an update, or use it once the original AT&T SIM was reinserted. If true, the reports would put to rest the greatest fear of many users: that unlocked iPhones would be bricked, or rendered completely inoperable.