Yum has a few things needing fixing. For example:

I have smolt-0.9.8.3-1.fc7 installed but if I do
yum install smolt
it replies
Nothing to do

Logically you would assume that this "Nothing to do" message means "I already have that package installed" but NO.

If I do a bogus yum install
yum install rambo
I also get
Nothing to do

So the generic reply 'Nothing to do' gives absolutely no hint as to what the result of your yum install command really was.

Hopefully the developers are looking at giving it some better response text. Not that I miss "Your program has performed an illegal operation and needs to close", but some small change to YUM would be nice.