There is a 'language detect' API written by Google which is used in all Google products (Gmail,
Translate, and also Reader). It can force the directionality of a text box based on the detected language
of the content: http://code.google.com/apis/ajax/playground/#language_detect
also In RSS feeds you can Lookup the "language" node of the feed and it is considered as RTL if it starts with ar, fa, ur, ps, syr, dv, he or yi.
To display text in right to left mode just use the "direction" CSS property with "rtl" value.

In the mean time I created a userscript that adds a "Toggle Direction" button to posts:
http://userscripts.org/scripts/show/172665

I only tested it on chrome, but I don't see why it shouldn't work on Firefox+Greasemonkey.
This is only a temporary solution until the TOR team fixes this.

You can expose a setting to enable/disable automatic RTL detection.
You can also add a setting for choosing the direction manually for a given post in cases where the automatic detection fails.

The original Google Reader did a pretty good job of finding out which posts to display as RTL.
I guess you can simply test if the RTL symbol to LTR symbol ratio >1.5 or something like that.

Right now the text is aligned to the left, and lines that mix english words/names are garbled up even though the same posts will look good in Google Reader.

Google developed an Apache licensed library that can guesstimate a text's direction:
http://closure-library.googlecode.com/svn/docs/closure_goog_i18n_bidi.js.html

Ideally you should test each block (paragraph/div) separately, making two passes - on the second pass any block that has no guesstimated direction (such as a div containing only an image) should be set to the direction of the paragraphs above/below it. That's my two cents :)

Not really, Anonymous. They would enable RTL for every post, even though most of them are LTR.

Do these help?

http://userstyles.org/styles/83447/theoldreader-rtl

http://userstyles.org/styles/76347/theoldreader-post-rtl

This is especially important for Arabic and Hebrew content and comments. Everything is aligned left, and mixing any English word in screws up the whole line.

3 votes!

Indeed, adding Right to Left support would be fantastic. And keep up the good work ;)