Any day there's a major operating system update always contains some excitement, but Wednesday's iOS 5 release contained more surprises than some iPhone and iPad users might have hoped for.

Based on reports from around the Internet, Twitter messages, posts on Apple's forums, emails sent to Macworld, some users have run into difficulty getting Apple's iOS update to install on their mobile devices.

It's impossible, of course, to get a read on just how widespread iOS 5 installations problems. Certainly, some Macworld editors were able to upgrade their iOS devices without much difficulty, particularly in the afternoon after the initial crush of iOS 5 updates subsided. Still, the volume of complaints about iOS 5 update issues seemed higher than what one might normally expect from a major software upgrade.

Joel Mathis's case seems typical of the problems other users were reporting: He downloaded the iOS 5 updates, aimed to install them on his iPhone and iPad, and at the restoring stage, iTunes repeatedly failed. "The iPad 'Joel's iPad' could not be restored. An internal error occurred," iTunes told him again and again. Mathis event as far as completely resetting his iPad's settings to see if that would help. It didn't.

It's not an isolated case. We've put in a call to Apple to see if the company was aware of issues people may be having with the iOS 5 upgrade, but the company hasn't responded to that request yet.

Apple certainly had a lot on its plate yesterday. In addition to releasing iOS 5, the company also released iCloud as well as three new iOS apps. It also updated several existing iOS and Mac apps, released Mac OS x 10.7.2 and Safari 5.1.1, and even updated the firmware for its Apple TV set-top box. That's a lot of software to be pushing live at once, even for a company Apple's size.

Wednesday's woes might conjure up memories for some iOS users of 2008's iPhone 3G launch. In addition to introducing a new phone on July 11 of that year, Apple also rolled out a mobile operating system update and launched its rebranded MobileMe service.

Activation delays marred the iPhone 3G launch, while MobileMe's debut was marked by so many glitches, the company wound up offering subscribers a free 60-day extension to make up for the problems they encountered.