Apple ios 6.1 Update.

[#1]

If you have recently updated your Apple iPhone, iPad, iPod or Apple TV to iOS 6.1, you may experience problems with your wireless connection, these problems may include:
 Poor wireless speed
 Unable to browse websites
 Wireless disconnections
   
Problems connecting to your wireless network such as a delay in re-establishing the connection when your device wakes from sleep mode.
https://discussions.apple.com/message/21083895#21083895

[#2]

Hmmmm!
I updated my iPhone 4 and my iPad 3 and my Apple TV on the day IOS6.1 appeared. Absolutely no problems.  
I also mod on a UK iPhone forum and nothing has been reported there!  
Perhaps this is limited to the US of A?
The usual cure for wifi problems is to delete the offending network and then to re-enter it as new.

[#3]

Not sure, SWMBO has an apple phone and she has been having problems with connecting to her wifi, Made her aware of this situation as I only came across this news tonight.

[#4]

two ipads and an apple tv updated on day of release with no issues either..