People spend a lot of time worrying about capitalization, especially in relation to meta tags.
No one wants to miss traffic, so some people have taken to listing every variation of a word in their meta tags. It gets even worse if you decide you need to include both singular and plural forms, but that's another issue. The simple answer is to relax and stick with lower case. That's because practically everyone searches in lower case. Besides that, only two search engines are completely case sensitive.