Currently, if you open a bold or italic tag in one paragraph and close it in a later one, everything works as you'd expect - everything is bolded / italicized as expected. However, if you do the same with an OOC tag, the font color reverts back to black at the end of the paragraph.
Example:
Starting bold.
Ending bold.
Ending OOC
For what it's worth (i.e., almost nothing), in IE7 those tags both behave in the same (wrong) way: the first line is bolded/blued and the second line is not.
After looking at the page source, this appears to be an issue with how browsers handle mismatched <b> tags compared to mismatched <span> tags. Which will be a very browser dependent thing, and probably not something which Gary and crew can easily fix.
The only solution I can think of off hand would be to have the messageboard code automatically close all open tags at the end of a paragraph and open them again at the start of the next. But that would require actually parsing the post, instead of simply doing BBcode-to-HTML substitutions.