It is an obvious reflection that so-called high wages are a transitory form of remuneration. Adaptation to the new methods of production and work cannot take place simply through social compulsion. ... If the situation were "normal", the apparatus of coercion needed to obtain the desired result would involve more than just high wages. Coercion has therefore to be ingeniously combined with persuasion and consent. This effect can be achieved, in forms proper to the society in question, by higher remuneration such as to permit a particular living standard which can maintain and restore the strength that has been worn down by the new form of toil. But no sooner have the new methods of work and production been generalised and diffused, the new type of worker been created universally and the apparatus of material production further perfected, no sooner has this happened than the excessive "turnover" has automatically to be restricted by widespread unemployment, and high wages disappear.
Gramsci, High-Wages, from ‘Americanism and Fordism’, in Selections From the Prison Notebooks, (p310)
The point of which is to show that the 'high-wages' which were a part of this form of capitalism were a necessary part of a coercive regime required to make Fordism work. Working on the automated (moving conveyor belt type) assembly line that was central to fordist factory production was so unpleasant that no one was prepared to do it at the perviously standard wage and so 'higher wages' had to be paid to make the whole system work. Gramsci's point is that these 'high-wages' are not a good thing as they are merely one part of a system for manufacturing consent to worse (ever more dehumanising) conditions of labour. High wages are the lash that spurs the worker on ever faster.
What then has this got to do with the web's world of social networks?
The post-fordist 'immaterial labour' (the leisure and consumption as work that Adorno, Marcuse, Biffo, Marazzi and many others showed was developing in the aftermath of the second world war and especially under neoliberalism [1970-2008]) also operated to create a new type of worker (literally you & I) enmeshed in a new apparatus of immaterial production (this, literally this which you are looking at now) which is engaged in the same process of excessive turnover in the immaterial as Ford's original was in the material. Just as the 'high wages' disappeared when the tactical deployment of capital that required them moved on so the products of immaterial production also disappear.
MySpace, Facebook, Twitter, this, the whole of the web, all permit a new type of renumeration (often passing under the label 'free') based on the use of services (media) - mainly communicative - that are themselves essential to the new methods of production and work that these services themselves represent. We are ingeniously persuaded to consent because the whole apparatus is given to us for 'nothing' as part of our participation on the web. However, this (literally this that you are looking at right now) is just one more tactical deployment of capital and when the strategic needs of capital move on this tactical deployment will disappear just as ford's high wages disappeared.
It is not that 'popularity' or 'fashion' has something to do with web services rising and falling but the movements of users and of profits and of the phantasies of capital we call 'share prices' that leads to these web services thriving or disappearing. MySpace's use of music, musical preferences and phatic interaction was outmanoeuvred by Facebooks use of a wider range of raw social interaction that encompassed what MySpace could do and Facebook in turn will be outmanoeuvred (by Google, by Apple, by someone else...) and it too will suffer the problems of excessive turnover that MySpace faced at the moment of its outmanoeuvring. The immaterial labour that went into MySpace was wasted, the immaterial labour going into Facebook will be wasted, as this is waste, because our universal adaptation to the new mode of production results in over production.
It is a good thing that email is old enough and simple enough to survive the forthcoming destruction of immaterial value that will be the result of the the restriction of excessive immaterial turnover as it will be useful to still at least be able to use the net to communicate.