If you have a need to set custom request headers like User-Agent or Host, here is how you do so via the EM client

http = EventMachine::HttpRequest.new(url)
  .get(:head => {"User-Agent" => "Custom Agent"})

After updating to 4.2.1 and untethered jailbreak via redsn0w on my iPhone 3g, I had two major issues. The first issue has to do with multitasking. The springboard would crash when using the fast switching. This was fixed by changing the following lines in /System/Library/CoreServices/SpringBoard.app/N82AP.plist

<key>opengles-1</key>

to

<key>opengles-2</key>

The next problem was mounting my iPhone in Ubuntu Linux. The error message will contain something about a timeout. If this is happening you probably need to re-pair the device by doing the following via the libimobledevice utils:

idevicepair unpair
idevicepair pair
idevicepair validate

This may be pretty basic, but figured it may be useful to others. According to the passenger docs, it will look for Apache in the $PATH environment variable. So to fix the Apache 2 not found error, you first need to find the install location. A very helpful command is “whereis” that comes standard on most *NIX systems. If you have whereis installed copy/paste the following into the command line

APACHE_PATH=`whereis apache | awk '{ print $2 }'`

That will set APACHE_PATH to the path returned from whereis. Before you continue, please make sure the path was set properly.

echo $APACHE_PATH

If everything looks good, update the $PATH environment variable.

export PATH=$APACHE_PATH/bin:$PATH

Then check path to ensure it was updated

echo $PATH