It may take me a little while to respond - but I always do!
It is SUCH a pet peeve of mine when I comment or even tweet to a fellow blogger and I get no response. Nothing. Ziltch. I don't even mind if it takes a few days...but not to have ANY response? It's just rude.
I'm not saying I'm perfect - I'm not. I'm sure there are a couple that fall through the crack. I hope not many. And if I've done it to you - I apologize!!
Is it common practice for you? Do you respond to comments and tweet from bloggers - even if they're new to your blog?