There was some confusion on IRC as to whether bitcoin addresses are opaque
or not.

https://en.bitcoin.it/wiki/Address

For the sake of argument let's say that opaque means that you can tell
nothing about the address by examining the characters.

My understanding was that they are NOT opaque, and that if that has
changed, it will invalidate much at least some wiki page, for examples at
least some of the following would now be false:

--------
"A Bitcoin address, or simply address, is an identifier of 27-34
alphanumeric characters" -- FALSE

"with the number 1 or 3" -- FALSE

"you can send bitcoins to a person by sending bitcoins to one of their
addresses" -- FALSE

"Addresses are created simply by generating random numbers and then
performing mathematical operations to derive matching pairs of "public" and
"private" keys" -- FALSE

"The probability that a mistyped address is accepted as being valid is 1 in
232, that is, approximately 1 in 4.29 billion" -- FALSE

"If you would like to validate a Bitcoin address in an application, it is
advisable to use a method from this thread rather than to just check for
string length, allowed characters, or that the address starts with a 1 or
3." -- FALSE

"For most properly-generated Bitcoin addresses, there is at least one
secret number known as a private key" -- FALSE

"They consist of random digits and uppercase and lowercase letters, with
the exception that the uppercase letter "O", uppercase letter "I",
lowercase letter "l", and the number "0" are never used to prevent visual
ambiguity" -- FALSE

"Some Bitcoin addresses can be shorter than 34 characters (as few as 27)"
-- FALSE

"Several of the characters inside a Bitcoin address are used as a checksum
so that typographical errors can be automatically found and rejected" --
FALSE

"The checksum also allows Bitcoin software to confirm that a 33-character
(or shorter) address is in fact valid and isn't simply an address with a
missing character" -- FALSE
--------

I also here that there is a LIKELY change from the base58 encoding ... when
was this established?

There's either been some bit changes to the fundamentals of bitcoin here or
there's been some misunderstandings.  It would be good to clear things up
as to what exactly an address is now beleived to be, and reflect that in
the wiki.