Recently, there has been an increased awareness of the impact queuing plays in the performance and design of high-performance packet switches. For instance, the importance of memory sharing and trunking is generally accepted by researchers and developers today, especially when one considers `real' traffic that is `bursty.' Burstiness can result from the sources themselves, and can be exacerbated by store-and-forward networks. In this paper, we address some new features and characteristics of queuing in optical packet switches. All of the fundamental results (e.g., the performance advantages of output queuing and the memory reduction of buffer sharing) still apply to optical packet switches. However, the limited state of optical technology (e.g., the lack of an optical random access memory) puts constraints on the architecture of optical packet switches. The lack of an optical random access memory led many in the past to propose hybrid switch architectures that exploit the advantages of both optics and electronics, using electronics for the queuing of packets. Here, we instead focus our attention on the fundamental performance limitations associated with `all-optical' packet switches, in which the packet buffering is implemented via fiber delay lines.