People are reporting receiving error code 414, when trying to download several iPhone Applications at once. Most users with this problem in the Apple Discussions Forum thread, found it occurred when needing to update more than 20 Apps.
Suggestions are running that this may be a bug in the iTunes Store system related to the "mature content" warnings Apple uses.
The ‚Äòfix‚Äô is to download the 17+ rated Apps one at a time, saving all your others for a mass download. This of course involves a little extra step. You have to check each app for it‚Äôs rating before downloading.
Updating on a more regular basis would obviously help as well.
It does not appear that the recent update to Snow Leopard addressed this issue. A future iTunes update will surely tackle the problem.