You can use LaTeX (google API rendering) in the Blogger text/HTML editor directly.

the same test of http://ex-ample.blogspot.com/2011/07/test.html
this test is based on the www.codecogs.com rendering used by http://userscripts.org/scripts/show/64270
LaTeX for Blogger w/ Undo in the Updated Editor (version codecogs).

Now "LaTeX for Blogger with Google Chart API" with google chart API rendering:
http://userscripts.org/scripts/show/105016

I use this LaTeX code:
e = \lim_{n\to\infty} \left(1+\frac{1}{n}\right)^n
------------------result:

------------------end