I have been slowly building up a collection of emulators for the Sharp Zaurus and only by coincident the Nokia 770. I finally finished building the project pages and thought I'd announce it here first.
Below are the links to each project page containing screen shots, downloads, patches, benchmarks with results, links for more information and source.
HP-48GX and HP-48SX (tested with Zaurus c860 and Nokia 770, reformatted for 640x480 screens):
http://sense.net/zc/x48
HP-42S (tested with Zaurus c860 and Nokia 770, new 640x480 skins (42C fantasy calculator) added with Zaurus keyboard hints):
http://sense.net/zc/free42
HP-35, HP-45, HP-55, HP-80, HP-21, HP-25, HP-32E, HP-33C, HP-34C, HP-37E, HP-38C, HP-38E, HP-41CV, HP-41CX, HP-11C, HP-12C, HP-15C, and HP-16C (tested with C860, some 640x480 friendly skins added for 35, 41CV, and 41CX. 11C-16C already 640x480 friendly):
http://sense.net/zc/nonpareil
I must add that emulators are no substitute for the real thing. I still have my 48GX and 15C on my desk and without thinking reach for them first. However, emulation on my Zaurus does make a good travel companion (i.e. small, fast, light, *replaceable*).