Ok - thanks for everyone's commments and patches. I've been pretty slack on the coding front lately but I'm going to remedy that with a new version of wpmail this week.
For everyone running PHP5 (Han's, etc) wp-mail ver 0.2 won't work. This is because of a problem with Pear's mimedecode objective stuff being messed up. I've fixed it and submitted the bugs to Pear, so basically it's fixed in wp-mail ver 0.3.
I'm just testing 0.3 now and if it passes by the end of the week I'll post it up. Stay tuned...