The mathematics or equations editor is a rather sad piece of work within the GDocs system. There used to be fair TeX / LaTeX functionality, but this was at first completely removed with the revamp of Apr/May 2010 and then only partially restored in Oct/Nov 2010. I think that nothing of substance happened with the equations editor since Oct/Nov 2010. Occasionally some bug is created and some time later it is fixed, but nothing structural is changed. There have been some improvements in the conversion to printed output or to pdf, but plenty of problems remain with that output.
I wanted to inventorize issues with the equations editor and went back through the Forum postings. I collected relevant postings, omitting items where a temporary bug is discussed or where someone just needs help or advice. For anybody's interest or entertainment or possible benefit, here is a bibliography (incomplete, no doubt) of forum conversations on the subject of mathematics editing in GDocs and going back in time to not earlier than Oct/Nov 2010.
I don't want to add much interpretation or commentary here, so just one remark: Presently my main recommendation to the GDocs team for the equations editor is to try hard to adopt a MathJax interface at the user end.
The main GDocs help page for mathematics editing is this one.
Here are the Forum conversations.
2012-02-16: When is Google going to put back latex editing into equation editor? And in the mean time, can your support clipboard operations that convert to and from latex
2012-01-21: Various serious rendering problems with the equation editor
2012-02-09: How do I get big fractions in Google Docs equations?
2011-11-06: Suggestion - equation editor transparency
2011-11-04: I use a program called MathType to make math equations. These equations will not upload correctly to Google Docs.
2011-10-31: Any plans for improved equation support in Documents/Presentations? (e.g. MathJax/LaTeX)
2011-10-25: Is there a good way to increase the font size in the equations? When I use the a/b equation, the fonts are too small.
2011-10-01: The printed document is different to how the document looks on screen
2011-09-29: just one question or suggestion. Do you have any plan to implement Latex support in docs? It will be nice to researcher
2011-09-28: How to retain latex info when downloading google doc containing equations?
2011-09-25: Is it possible to enter piecewise functions in Google Docs equation editor?
2011-09-19: Create stacked fractions in equations without text being too small?
2011-09-14: When inserting Equation, I had found there is no "Min" and "Max" function.
2011-09-11: Multiple equations on separate lines in 1 editor
2011-09-04: Cursor displayed in wrong position when editing equations
2011-08-28: Google Equations Loading Improperly across all browsers
2011-08-22: Increasing Equation Editor Font-Size
2011-08-15: Is there a way to upload a Word document into Google doc if the word document has equations in it?
2011-08-13: How do I have my document NOT completely chew up my equations when printing or saving as PDF?
2011-08-10: Is it possble to ad the symbols for Ray, Line, and congruent in equation editor for google docs?
2011-08-08: Unable to print Equations
2011-06-07: Is there an infinity symbol anywhere in the equation editor? Also missing a matrix tool
2011-05-23: how to import .odt .doc and .docx with formulas (equations)?
2011-05-13: Equation and text overlap when re-opening a google document
2011-05-13: In google document with equations, then if I use "File-->Download as -->PDF", the equations are unclear!
2011-05-11: How do I export or print the documents with equation correctly. The downloaded pdf has all the equations blurred.
2011-05-10: How do I insert double struck (blackboard bold) characters into a Google Docs equation?
2011-04-17: Characters in the fractions don't have the same size as the rest of terms
2011-04-15: 3 bugs affecting me the most
2011-04-05: Equation Editor Changing Size and Content of Symbols When Printing
2011-03-30: There is no "closed surface integral" sign in the equation editor, just a closed curve one.
2011-03-26: How do I retain the formatting in my PDF files when converting them to Google Docs? Google Docs trashes PDF formatting.
2011-03-19: Missing LaTeX symbols in equation editor
2011-03-19: is there any hope that google will put back the vital option to edit math formulas using latex?
2011-03-08: Missing item: Matrix support in Equations
2011-03-04: I want to insert an array in my equations.
2011-02-28: Most urgent issues for scientific preprints in GDocs
2011-02-17: A one-click design for inserting special characters
2011-02-04: Appearance of equations in print documents look unusable for professional documents...
2011-01-24: Spacing errors in mathematical equations
2011-01-17: How can I make a dot over a single letter?
2010-12-23: Wishlist B. Editing equations
2010-12-19: Suggestion for dealing with special characters in mathematical text
2010-12-13: LaTeX commands for mathematical formulas in Google Documents.
2010-12-12: Roman font in equations in Docs
2010-12-12: Additional special symbols through an escape sequence