By request a post that may create the biggest backlash since I declared myself Unix free.
LaTeX is a great system for mathematical documents...for the 1980s. But the computing world changed dramatically and LaTeX didn't keep up. Unlike Unix I can't give it up. I write papers with other computer scientists and mathematicians and since they use LaTeX so do I. LaTeX still has the best mathematics formulas but in almost every other aspect it lags behind modern document systems.
WSYWIG: I love seeing the final document as I write it. There are front ends to LaTeX that approximate this but they produce LaTeX code that make it near impossible to collaborate unless everyone uses the same editor and we don't. "Code" is the right word, I have to compile a LaTeX document then start a separate program to see it.
Collaboration: The very reason I'm stuck with LaTeX is its greatest weakness. We all have different macros, style files and bibtex formats (and some don't use bibtex at all). We all have to agree in the beginning which of our homegrown stuff we want to use and merging already written documents is a bear. How often does some one send you a LaTeX document and you have to email back that they forgot some style file?
LaTeX documents are saved as text files which have different formats on different machines. I hate seeing ^M at the end of every line. Some people to break up LaTeX lines at reasonable places, other people don't messing up my editor and trying to figure out what my co-author has changed.. At least email attachments avoid the old ¿From problem.
Microsoft Word has a great system for tracking revisions. Google Docs lets people edit at the same time. Nothing close to either for LaTeX.
User Friendly: LaTeX is not user friendly. Try opening a text editor and (without looking at an old LaTeX document) write a LaTeX document to say "Hello World!" that will compile on the first try. Now go to Google Docs, create a new document and type "Hello World!". See the difference. Don't even get me started on creating a table.
Backward Compatibility: In the early 90's, LaTeX went through a major upgrade. There was a compatibility mode that claimed to be fully backward compatible. Not even close. Then they changed the font system, rendering my old documents unreadable. Luckily LaTeX hasn't changed significantly since then.
It's not difficult to convert between Word, Docs and most other document systems but nearly impossible to move to/from LaTeX.
I don't use LaTeX when I don't need to. I usually use Word or Docs for recommendation letters and other documents without much formulas and references including my upcoming P/NP book.
What we need is a way out of LaTeX, add-ons to Google Doc that make it as nice for math as LaTeX, and the ability to import old LaTeX documents, style files and bibtex files. Not holding my breath.