Il padrone del vapore e' colui chi in un paese detiene il potere economico. Non so se nel contesto la parola tycoon puo' andare bene.
PS: Scusa gli accenti, ma sto scrivendo con una tastiera inglese.


--------------------------------------------------
Note added at 23 mins (2007-06-15 14:06:03 GMT)
--------------------------------------------------

WORD HISTORY It has been claimed that in today's global economy some business leaders have more power than heads of states. It is etymologically fitting that such leaders are sometimes called tycoons. Tycoon came into English from Japanese, which had borrowed the title, meaning “great prince,” from Chinese. Use of the word was intended to make the shogun, the commander in chief of the Japanese army, more impressive to foreigners (his official title shōgun merely meant “general”). It worked with Matthew C. Perry, who opened Japan to the West in 1854; Perry carried out his negotiations with the shogun, thinking him to be the emperor. In fact, the shogun did rule Japan, although he was supposedly acting for the emperor. The shogun's title, taikun, was brought back to the United States after Perry's visit. Abraham Lincoln's cabinet members used tycoon as an affectionate nickname for the President. The word soon came to be used for business and industry leaders—at times being applied to figures like J. P. Morgan, who may indeed have wielded more power than many princes and presidents.

I think it refers to individuals who do as they please... In this context I would say the expression means that they are ruthless financiers who are above the law. Perhaps you've read the excerpt below in your searches but will put it in anyway just in case as I think it sums up the idea quite nicely. For now the only idea I can come up with along these lines is "untouchables", I daresay someone else will come up with a better suggestion though!

--------------------------------------------------
Note added at 45 mins (2007-06-15 14:28:07 GMT)
--------------------------------------------------

Just another note:
the article in this link below also reinforces the idea that these "padroni del vapore" are more than just powerful and wealthy magnates, but that they are somehow slightly dodgy with it.... the word wiseguys comes to mind...:-)
I've also found an article (link below) where participants of the Bilderberg group are referred to as "padroni del vapore" which also suggests the link between this expression and underhand dealings.

http://www.ilgiornale.it/a.pic1?ID=185646

http://it.altermedia.info/economia/i-padroni-del-vapore_1378...

I agree with your localization: 'captain of industry' is the actual meaning of the concept, since your dealing with bankers, I would try to specify that they do so through their capital/funds/cash allocation.

It's from a title of a film (1951) by Mario Matolli. The film was called Master of the Vapor (too litteral). In wordreference I found: "Berlusconi il padrone del vapore, che tutto puo".
High rollers is for casino players, top brass for army officers, just like warlords. Taipan is like tycoon, but this word is Chinese, big enchilada is USA - based on a Mexican food. Oligrarchs are Taipans or Tycoons - only this time the term is used in Russia and Israel (for such people when the immigrate to Israel).
I prefer the High and (the) Mighty but Moguls and indeed magnates are OK. Magnates, magnus - a Latin orgin but the modern use is Polish. It depends who you translate for.