On September 25, I posted on "Character amnesia and the emergence of digraphia", which occasioned a vigorous debate. A few of the commenters thought the essay in question wasn't actually written by a student. Be that as it may, this habit of replacing characters by Pinyin is becoming more and more common, especially among young students. Let us look at this scene from the Chinese documentary "Qǐng tóu wǒ yī piào" 请投我一票 (Please vote for me) at (34:29).
As part of an exercise in democracy, the boy is practicing the speech he wants to give since he's running for bānzhǎng 班长 ("class monitor"). As you can see, he replaces a couple of characters with the Pinyin equivalents.
Even adults do this in casual, informal, private situations (e.g., writing down shopping lists). Of course, they normally wouldn't want others to see them spelling things in Pinyin, for fear of being accused of not being fully literate in characters or of selling out the motherland to a foreign device. Never mind that Hanyu Pinyin is the official Romanization of Modern Standard Mandarin and that there are also official orthographic rules for word division, punctuation, and so forth). Here's the latest version (2012) of the orthographic rules.
An English translation (by John Rohsenow) of the previous edition (1996) of the orthographic rules is printed at the back of all ABC Chinese-English dictionaries from the University of Hawai'i Press.
Because of this increasing tendency for people to replace characters they cannot write with Pinyin (very much like kana in Japanese), not to mention the overwhelming use of Pinyin for inputting in computers and on cellphones, I think it is fair to speak of an emerging digraphia.
By the way, the documentary mentioned above begins with students being asked what "democracy" (mínzhǔ 民主) and "voting" (tóupiào" 投票) are. They don't have a clue.
[Thanks to Matt Kosko]