I wish someone would become the authority on this subject and just tell it like it is, and start enforcing it... The worst thing to me is when people mix it up in the same application or worse yet same class.
I've see some pretty horrible stuff with txtName, NameTextBox, name and textBox1 all used on the same form... yuck.
Where I work we have a standards document that tells us how to do it, where to do it, and I think only 20% of the people even care to try and conform.
I usually will change something if Fxcop yells at me.
http://en.wikipedia.org/wiki/Naming_conventions_%28programming%29
Capitalization Styles
Note that:
Microsoft .NET recommends UpperCamelCase (aka "Pascal Style") for most identifiers. (lowerCamelCase is recommended for parameters).