Apple has released iOS 8.1.1 for download, after releasing the beta for developers exactly two weeks ago, which noted some performance increases for the iPhone 4S and iPad 2. The download is 64MB for the iPhone 6, as seen below:
Below are the direct download links:
Apple TV 3 (AppleTV3,1) version 7.0.2 (Build 12B435), Download
Apple TV 3 (2013) (AppleTV3,2) version 7.0.2 (Build 12B435), Download
iPad 2 (Wi-Fi) (iPad2,1) version 8.1.1 (Build 12B435), Download
iPad 2 (GSM) (iPad2,2) version 8.1.1 (Build 12B435), Download
iPad 2 (CDMA) (iPad2,3) version 8.1.1 (Build 12B435), Download
iPad 2 (Mid 2012) (iPad2,4) version 8.1.1 (Build 12B435), Download
iPad mini (Wi-Fi) (iPad2,5) version 8.1.1 (Build 12B435), Download
iPad mini (GSM) (iPad2,6) version 8.1.1 (Build 12B435), Download
iPad mini (CDMA) (iPad2,7) version 8.1.1 (Build 12B435), Download
iPad 3 (Wi-Fi) (iPad3,1) version 8.1.1 (Build 12B435), Download
iPad 3 (GSM) (iPad3,2) version 8.1.1 (Build 12B435), Download
iPad 3 (CDMA) (iPad3,3) version 8.1.1 (Build 12B435), Download
iPad 4 (Wi-Fi) (iPad3,4) version 8.1.1 (Build 12B435), Download
iPad 4 (GSM) (iPad3,5) version 8.1.1 (Build 12B435), Download
iPad 4 (CDMA) (iPad3,6) version 8.1.1 (Build 12B435), Download
iPad Air (Wi-Fi) (iPad4,1) version 8.1.1 (Build 12B435), Download
iPad Air (GSM) (iPad4,2) version 8.1.1 (Build 12B435), Download
iPad Air (CDMA) (iPad4,3) version 8.1.1 (Build 12B435), Download
iPad mini Retina (Wi-Fi) (iPad4,4) version 8.1.1 (Build 12B435), Download
iPad mini Retina (GSM) (iPad4,5) version 8.1.1 (Build 12B435), Download
iPad mini Retina (CDMA) (iPad4,6) version 8.1.1 (Build 12B435), Download
iPad mini 3 (Wi-Fi) (iPad4,7) version 8.1.1 (Build 12B436), Download
iPad mini 3 (Cellular) (iPad4,8) version 8.1.1 (Build 12B436), Download
iPad mini 3 (China) (iPad4,9) version 8.1.1 (Build 12B436), Download
iPad Air 2 (Wi-Fi) (iPad5,3) version 8.1.1 (Build 12B436), Download
iPad Air 2 (Cellular) (iPad5,4) version 8.1.1 (Build 12B436), Download
iPhone 4s (iPhone4,1) version 8.1.1 (Build 12B435), Download
iPhone 5 (GSM) (iPhone5,1) version 8.1.1 (Build 12B435), Download
iPhone 5 (CDMA) (iPhone5,2) version 8.1.1 (Build 12B435), Download
iPhone 5c (GSM) (iPhone5,3) version 8.1.1 (Build 12B435), Download
iPhone 5c (CDMA) (iPhone5,4) version 8.1.1 (Build 12B435), Download
iPhone 5s (GSM) (iPhone6,1) version 8.1.1 (Build 12B435), Download
iPhone 5s (CDMA) (iPhone6,2) version 8.1.1 (Build 12B435), Download
iPhone 6 Plus (iPhone7,1) version 8.1.1 (Build 12B436), Download
iPhone 6 (iPhone7,2) version 8.1.1 (Build 12B436), Download
iPod touch 5G (iPod5,1) version 8.1.1 (Build 12B435), Download
Update: Here are the full iOS 8.1.1 release notes: