The iOS 4.3.1 Software Update is now available for download via iTunes. Per Apple's web site, "This update contains improvements and other bug fixes including:

• Fixes an occasional graphics glitch on iPod touch (4th generation)
• Resolves bugs related to activating and connecting to some cellular networks
• Fixes image flicker when using Apple Digital AV Adapter with some TVs
• Resolves an issue authenticating with some enterprise web services

Products compatible with this software update:....

• iPhone 4 (GSM model)
• iPhone 3GS
• iPad 2
• iPad
• iPod touch (4th generation)
• iPod touch (3rd generation)

This update contains security content originally included in previous iOS Software Updates."