Η έκφραση (κυρίως το "tip of the hat") είναι αρκετά παλιά, αλλά θεωρείται ότι αποτελεί διαδικτυακή αναβίωση στη μορφή hat tip to. Κοίταξα τα γκουγκλοβιβλία και πράγματι κυκλοφορεί εκεί μετά το έτος 2000, ενώ δεν είναι πολλά τα παλιότερα ευρήματα για tip of the hat to. Στο OED το παλιότερο είναι του 1976:
In fig. phr. a tip of the hat (or cap), an acknowledgement or mark of respect, in recognition of achievement, thanks, etc.
1976 U.S. News & World Rep. 7 June 45/1 For King Juan Carlos I, his visit to the U.S. is more than a tip of the hat to the American Bicentennial. 1977 Washington Post 13 Jan. 14/3 A tip of the hat to the friendly people who make the skies so friendly for United Air Lines.
Εμείς βέβαια χρησιμοποιούμε το γαλλικό σαπό και την παλιά έκφραση του βγάζω το καπέλο για να εκφράσουμε τις ευχαριστίες μας, τα συγχαρητήριά μας και το σεβασμό μας (ρισπέκ/τ!).
Στο αναπόφευκτο λήμμα της Wikipedia γράφει:
In the 2000s, the term "hat tip" (often abbreviated to "HT" or "h/t") rose to prominence in the blogosphere to acknowledge someone who has made a significant contribution toward an effort, or someone who drew attention to something new or interesting. It is considered good netiquette when sharing a link or news item to give a hat tip to the person from whom you learned of the item. The on-line versions of the Wall Street Journal and the New York Times regularly give hat tips to users who bring ideas for articles to their attention.
http://en.wikipedia.org/wiki/Hat_tip
Οι Μακμίλαν δημοσιεύουν μακροσκελές άρθρο για το «νεολογισμό». Αξίζει:
Regular users of the Internet, bloggers, Facebookers, Twitterers the world over, are faced with a daily challenge – how to use written language in a "conversational" way but without access to facial expressions, arm movements and all those other non-linguistic tools we'd use in the real world to get the right message across. Conversational nuances are emulated in the online universe in various ways, from smiley faces and emoticons through to initialisms such as LOL and OMG, or descriptive words like facepalm (a way of showing that you feel frustrated or embarrassed). A further example of the latter type which appears to be gaining ground in recent times is the expression hat tip.
If in the course of their discussion someone uses the term hat tip in relation to a particular person, then they are acknowledging that said person has brought something to their attention, usually by providing new information or pointing them in the direction of another relevant source. As the citations above illustrate, the expression often appears in the distribution …(a) hat tip to X…, where X is the person to be acknowledged. Though most common in blogs, discussion forums and other kinds of social media, hat tip is increasingly popping up in online text generally, where it also sometimes functions as a more general acknowledgment that a person or organization has made a significant contribution to an effort or achievement. The same expression sometimes appears in phrasal rather than compound form as tip of the hat, and in social media contexts it's also often abbreviated to HT or h/t.
Background – hat tip
Use of the expression hat tip as a form of acknowledgement in online contexts first began to appear in the early 2000s, and can be thought of as one implementation of the wider concept of netiquette, a polite way of communicating with other people when using the Internet.
The expressions hat tip and tip of the hat go right back to the 19th and early 20th centuries, when in western societies it was customary to wear a hat. Friends or acquaintances, when walking along the street or meeting at a gathering, would lift or tip their hats to each other as a kind of non-verbal greeting, doing so in preference to exchanging words. Hat tipping was largely the preserve of men, and was sometimes used to emphasize social distance – someone lower down the social scale would be obliged to fully remove his hat, whilst his superior merely touched his in response.
It seems a bizarre twist, then, that the expression hat tip should have gained ground so many years later, in a generation where hat-wearing, for most people at least, is no longer considered the norm for everyday attire. The expression also has a verbal counterpart tip your hat to someone, used mainly in informal US English and meaning 'to tell someone that they should be proud of what they have achieved'.
http://www.macmillandictionary.com/buzzword/entries/hat-tip.html