Something like Pickpocket would work OK only if you have access to an internet connection. What I am talking about would be a way to transfer files from PocketPC-to-PocketPC using a wireless connection between the two units. That is, without an internet connection or an access point to connect to. I envision two people with PocketPCs sitting in the same general vicinity establishing a wireless connection between the 2 units (e.g., ad hoc mode) and then having the ability to send files or messages to each other. IR can do something like this in a limited way, but you need close proximity and line-of-sight to get it to work. IR is also slower than an 802.11x connection would be.
I am rather surprised that such an ability is not already a common feature of wireless connections, since it seems so appealing and useful...!