As a professional childminder of 15 years, and looked after some families for 10 years, and over 10 sets of siblings. I would like to add to what Rhubabrb said about childminders. In my experience those who go to playgroups/drop in, toddlers etc every day as some do, are basically avoiding being in the home with their charges doing what they should be doing - activities at home.
I know a lot of c/m's who do so and happily admit that they want to keep them out of their house so it doesn't 'get messed up'. I think it is appalling and would advise people to avoid c/m's who go to groups every day. It might sound great, - oh, we go out everyday, etc, but where do they go?
Children need a quiet calm environment, with the attention of a carer, time to read stories, learn new skills, all the things that being at home can provide, as well as meeting other children and making visits to aprks etc. not the constant noisy bustle and aggro of kids fighting over a bunch of grotty broken toys, on a daily basis whilst the carers sit round gossipping (I've seen it, believe me) (Mind you nannies do the same in Macdonalds, and ignore the babies in their pushchairs whilst they talk about make up, boyfriends and soaps!) but that's another story.
I do believe that babies are better at home or a home like environment, with a strict ratio of carers, not as part of a larger group setting than a nursery for the first 18 months and some new research due to be published next year will show that.
I am more than happy if some of my little ones go off to nursery at about 2.5 ish as they can do all the things I don't necessarily want to do all the time - have a water / sand tray out permanently, have paint out everyday. But I plan my activities carefully and we do follow a theme. This term we are doing 'all about myself' talking about growing, measuring, what we can do, or can't quite do yet etc.
Like most things there are good and bad nurseries and childminders, you just have to go with what you feel suits you and your child, we always have the good intentions of our children at heart.