Official support for tethering is still one feature conspicuous by its absence from the Palm Pre's abilities, and the last we heard Palm were cautioning tweakers not to unofficially enable it lest Sprint get upset. If, though, the promise of sharing all that EVDO Rev.A goodness is just too good to miss, and you fancy some MiFi-style WiFi hotspot action, then homebrew app My Tether is the answer.
Video demo after the cut
My Tether turns the Pre into either a wired USB or wireless Bluetooth modem, or a WiFi hotspot. It can be set to use WEP encryption over WiFi, together with disabling the Pre's sleep mode so as to avoid shutting off the data connection (as well as turning off the display to save battery).
You'll need to root your Pre in order to install My Tether, however, which requires a little more effort than loading a standard "official" title. Happily there's a useful tutorial here which explains just how to do that. Remember, if Sprint spot you using your Pre as a tethered modem they're unlikely to look on it happily, and could charge you for the data out-of-package or even cut off your connection altogether. You attempt hacks such as My Tether at your own risk.