Growing up in the 1980s, my perception of guitarists in rock bands was simple: if a person sang lead vocals and played guitar, he/she only played rhythm guitar. I never saw a singer/guitarist play a lead guitar solo. Solos were played by a lead guitarist who normally didn't sing (not even backing vocals).
So when I saw Nirvana performing in the "Smells Like Teen Spirit" video, I was confused. Where was the fourth member that only played guitar solos? A lead singer/guitarist could also play lead? Wow!
After seeing Manic Street Preachers, Pavement and Superchunk in live settings, I realized that this activity is very prevalent. What I think is amazing is that these singers sing their heads off (yes, even in his conversational singing voice, Stephen Malkmus still sang his head off) and play leads at the same time. These leads aren't made up of "liquid fingers," but they are more than bends and single notes.
I wonder how such coordination is possible. Then again, I'm sure there are people that wonder how drummers can coordinate playing a drumset.