I finally figured it out at about 3 am. What I was looking for was the blog, and forum links, but after much reading and poking around, I discovered that they are NOT included in the install.
I guess that the plugin manager must refer to some sort of integration "bridge" when it says that these were installed (and published) but the components themselves are not.
For anyone else out there, (unless you're much smarter than I)...do not try to install mamblog on a 1.5 install, even in legacy mode. I did, and it created a birdsnest of errors that I could only fix via ftp and phpmyadmin.
I'm new to CB, and trying to digest a lot in a hurry for a client, so blame myself for being overly eager. I will say though, that looking at how many people had similar issues (menu items) I didn't feel like the lone ranger on this.
Do you know if the 'bridges' will be updated to work with 1.5 components? Perhaps they should be excluded from RC2 for 1.5, or at least 'greyed out'...just a suggestion, and it may have been covered before.
Mark