Queued simply means that someone with a file you desire has noted that you wish to download a file from them and has added you to their
UpLoad Queue...
When you are Queued an UpLoad Slot is reserved for you and as soon as the person with the file you want has an open UpLoad Slot, they will begin transferring the file to you.
A whole lot better than the 'old days', believe me !
p.s. Some clients that are operating within the Gnutella Network are notorious for problems with UpLoad Queueing... You will probably learn fairly quickly just which clients are going to be a problem...
