I've been trying to troubleshoot another problem, in the course of which I:
1) Wiped my Palm profile from my Verizon Pre 3 and reinstalled it, in the course of which I re-entered my various account passwords -- no problems (a couple of weeks ago).
2) Switched my Palm profile to a different Verizon Pre 3, again re-entering my account passwords -- trying to enter the LinkedIn account password gave me an error (Saturday night).
3) Switched to a Verizon Pre 2 using a different Palm profile, re-entering my account passwords -- trying to enter the LinkedIn account password again gave me an error (yesterday). Trying to enter it in the Accounts program just now gives me a "Bad request" error.
So yeah, it appears that with the past couple of weeks, something has gone off the LinkedIn reservation.