I've been having this problem with google maps for some time. I had it installed but it wouldn't update saying that it isn't signed correctly. I was having the same problem with google voice search. So I found a thread here and I used the terminal to rename google voice search to voice.apk.old or whatever and rebooted and it installed just fine from the market. I figured I would try the same thing with maps but it didn't work. So I tried reinstalling the back I had with Astro and that didn't work either. The error its giving me is "installation failed. Unknown reason -8" Can anybody help me? I use google maps all the time. Thanks!