It seems that an unwanted side effect of installing iPhone OS 3.1 is that is dramatically reduces battery life for some users.
Apple's support forum is packed with disgruntled users. Here are a small selection of comments:
"The phone is using 10-12% of the battery every hour of standby ..."
"I went to sleep ater upgrading with the battery at 100% and woke up six hours later to find it at 55%. Screen off, didn't receive any phone calls during the night, wi-fi and bluetooth off, and 3G on (usually it would be above 90% in that same scenario)."
"in 2 hours lost 20% with 2 short calls, 3G and push on, wifi off. who said the 3.1 should improve battery life??"
"I dropped 70% in 3 hours with only 10 mins of calls."
"I used to come to the office with my phone at 100%, not use my phone all day and leave with it at 95% percent. Today, after the update, it's at 72% and I haven't used it at all."
At this stage it's too early to guess as to what the problem might be, but it seems that Apple is taking the issue seriously. A number of affected users have been contacted by AppleCare support and asked to answer a series of questions concerning handset usage. As part of the email users are also invited to install a battery life logging utility which sends back battery telemetry to Apple. Hopefully Apple can use this information to post a fix.
Battery life isn't the only issue plaguing users. Others are complaining about random freezes and lock ups (known as coma mode).
Anyone here suffering from battery life issues post iPhone OS 3.1? If you're experiencing issues I'd head over to the support forum and voice your troubles.