Microsoft support document 955020 addresses the possibility that Vista's spellchecker may mistakenly claim the names Friendster, Klum, Nazr, Obama, and Racicot are misspelled. It offers an updater which will fix this problem.
The package which adds five additional words for the built-in dictionary consists of eight DLLs totalling 56 MB. By comparison, William Shakespeare's complete works contains over 905,000 words and is 5.3 MB.
The manual workaround is to type a word, right click it and select "Add to Dictionary".
In older news: Microsoft addresses software accessibility.