I don't know about other European countries, but at least in Germany that's already a very real thing and has been for decades.

See http://de.wikipedia.org/wiki/Urlaubsgeld (use google/chrome translation).

Not everyone gets it, it usually depends on your (or your union's) salary negotiations with the employers.

While the Vacation Money is typically paid in June for the summer vacation, many companies also offer another an extra salary (or only a certain percentage of your regular monthly salary) in December for your christmas expenses.