In this post on the Dokeos blog, there's a comparison of the mbstring function and the iconv library as it pertains to their use on multi-byte strings.

I was wondering today why use mbstring rather than iconv in Dokeos, and honestly I didn't remember exactly why I had chosen mbstring in the past, but finding information about the *differences* between the two. [...] Searching a bit more, I found a PPT presentation from Carlos Hoyos on Google.

Essentially, it boils down to how the library is integrated - mbstring is bundled and iconv is pulled from an external source. So, if you're looking for maximum portability, he recommends mbstring.

In this new post on the SitePoint PHP Blog today, Harry looks at why it's "living dangerously" to use PHP with UTF-8.

Quick oneā€"knocked up a list of "dangerous" functions and functionality in PHP, in relation to the use of UTF-8, available at http://www.phpwact.org/php/i18n/utf-8. These are for a "default" PHP setup without the mbstring overloading or PHP6 (where charset problems "magically vanish" ;) ).

This follows on from (unfinished) stuff here on charsets (tending towards UTF-8), which should help explain some of this.

He also notes that you can't rely on mbstring to be there, so he offers an alternative...