Presently there are a total of 2,807 photos waiting to be processed on the upload page. At the present time the administrator of Airliners.net is working to fix some bugs in the code that runs this site so there may be a delay in processing these photos.
Here's a short run-down of the process itself. The processing of photos goes through two stages:
1) You upload your photos and the're reviewed by pre-screeners. They verify the quality of the photo and have the prerogative of rejecting the photo or letting it pass to final verification by the admin of Airliners.net. If your photo(s) is(are) rejected then you'll receive an e-mail stating the reasons. If there is no word it may be safe to assume that the photos have "passed the first screening". At times when the processing queue is short (small, whatever), then the site's administrator may look into the batch of photos that screeners haven't even viewed yet.
2) Johan, the site's administrator reviews all photos in the final queue and either accepts or rejects photos based on a number of reasons - this is considered the second or last screening. Either way, should your photo be accepted or rejected, you'll receive an e-mail stating so.
Hope this helps and good luck,