It appears that Apple had a much larger supply of 4.7-inch iPhone 6 units available for pre-order. The 5.5-inch iPhone 6 Plus model sold out the same day pre-orders went live. Apple is currently showing a 3-4 week shipping estimate on those models.
If you want to get an iPhone 6 now you will have to wait in line on launch day. Doors open at 8:00 a.m. on Friday, September 19th.
Did you manage to get your pre-order processed in time? Has it already shipped? Let us know in the comments and please stay tuned to iClarified on Twitter, Facebook, Google+, or RSS for updates.