Length matters?

According to Answers.com website ("Ask us anything'), the longest names are:

Person's Name
The longest name to date is Adolph Blaine Charles David Earl Frederick Jack Gerald Hubert Irvin John Kenneth Lloyd Martin Nero Oliver Paul Quincy Randolph Sherman Thomas Uncas Victor William Xerxes Yancy Zeus Wolfeschlegelsteinhausenbergerdorft Senior [746 letters]

The longest one-word name is of a young Hawaiian boy named Kananinoheaokuuhomeopuukaimanaalohilo [35 letters]. The name means "The Beautiful Aroma of My Home at Sparkling Diamond Hill is Carried to the Eyes of Heaven". In Hawaii, it is the custom to give children long, descriptive names. Dont worry though, they call him Joe, of all things, for short.

Place Name
The longest place name is the actual name of the city Bangkok, in Thailand :

Krungthepmahanakonbowornratanako-
sinmahintarayudyayamahadilopono-
paratanarajthaniburiromudomrajni-
wesmahasatarnamornpimarnavatarsa-
titsakattiyavisanukamphrasit (155 letters)

This translates to "The land of angels, the great city of immortality, of divine gems, the great angelic land unconquerable land of nine noble gems, the royal city, a pleasant capital place of the Royal Palace, eternal land of angels and reincarnated spirits predestined and created by the highest Devas."

The longest place name in an English-speaking country, though not an English word, is Taumata­whakatangihanga­koauau­o­tamatea­turi­pukakapiki­maunga­horo­nuku­pokai­whenua­kitanatahu [85 letters], the Māori name for a hill close to Porangahau, south of Waipukurau in southern Hawke's Bay, New Zealand. 

The 58-letter name Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch is the name of a town on Anglesey, an island of Wales. In terms of the traditional Welsh alphabet, the name is only 51 letters long, as certain digraphs in Welsh are considered as single letters, for instance ll, ng and ch. It is generally agreed, however, that this invented name, adopted in the mid-19th century, was contrived solely to be the longest name of any town in Britain. The official name of the place is Llanfairpwllgwyngyll, commonly abbreviated to Llanfairpwll or Llanfair PG. I had to toss this one in for my Welsh ancestors.

And the old joke: The longest word in English is smiles. Because there is a mile between the first and last letters.  Another version offers beleaguered, because there is a league between ... well, you get the idea. A league, for those unfamiliar with the term, is about three and a half miles.

As for Bart's word up there, Pneumonoultramicroscopicsilicovolcanoconiosis [45 letters] is an English word that refers to a lung disease that is otherwise known as silicosis. It is the longest word in the English language published in a dictionary, the Oxford English Dictionary.
According to the Oxford English Dictionary, the word refers to "an artificial long word said to mean a lung disease caused by inhaling very fine ash and sand dust."

The OED calls it an artificial word because it was created in 1935 for the sake of a puzzle. 

When I was a wee lad, we thought the longest word was antidisestablishmentarianism, which is certainly one of the longest real English words ever in use.

Antidisestablishmentarianism is a political philosophy that is opposed to the separation of church and state. The term originated in the context of the nineteenth century Church of England; antidisestablismentarians were opposed to proposals to remove its status as the state church of England. The term has largely fallen into disuse, although the issue itself is still current. 

Oddly, as children we were led to believe that the word applied to people who were against the church. I have a theory about how this misunderstanding arose, but this post has already gone on too long, don't you think?