See this blog post on Pinyin.info. The webmaster there wrote that post in response to an inquiry from me asking if he had a list of texts that were written solely in Pinyin, not in Chinese characters. That, in turn, was prompted by an argument that I had with one of my teachers and some of my classmates about the necessity of Chinese characters.
It's an argument I've had before. As much as I'm fascinated by them, and as much as I'm proud of how many I've learned and know how to write (last count: just over 2800), I hate them. I think it's a ridiculous, inefficient, and burdensome writing system. So, occasionally I'll get into a discussion where I'll suggest that they should be completely scrapped in favor of Pinyin, which is the phonetic writing system based on the Roman alphabet. Whenever I suggest this to a Chinese person, or even a foreigner whose studied Chinese for any amount of time, the response is amused skepticism, to put it mildly. 不可能! (Bù kěnéng! No way!)
No one here has even considered the possibility, and when they first consider it, it seems patently absurd. The problem as they see it is that the written characters contain much more information than just the pronunciation. In a nutshell, for every syllable in Mandarin Chinese, there are many possible characters. What they fail to take into account though, is that in standardized Pinyin, capitalization and word breaks are also brought into play, and have a powerful affect on reducing ambiguity.
What it boils down to is this: if a listener could understand something read in Mandarin (without seeing it written) then he or she would be able to understand the same thing written in the phonetic alphabet of Hanyu Pinyin. Note that this doesn't apply to obscure texts deliberately obfuscated, or to ancient Chinese, but it does apply to modern-day texts written in the vernacular.
I wish I had time to titivate (Merriam-Webster's word of the day today!) this post with lots of links to bolster some of my claims above, but I don't.
Update: I added a del.icio.us tag in-pinyin to track these babies.