this is how I figured out it was acting weird.... I uninstalled g+ messenger, and didn't know it would ALSO uninstall g+. When I went in to reinstall g+, it would never load and allow me to install. All the other apps are working fine today....but still no luck with g+ so maybe it's not the market and something is just screwed up with google apps today.
That may require a Factory Hard Reset to fix, but you might try first: From a home page/menu/settings/applications/manage applications/all/market/clear cache/clear data. If I recall, you will have to log back into the market and it will take a few minutes to resync, but then perhaps it will let you reinstall your app. If not, I think a reset is going to be needed.