Programming Languages – Languages Supporting Unicode Logic Operators

Yes, it is in Erlang. =/= means exactly not equal to, that would be somewhat equivalent to !==.

See more subtle differences (such as =< instead of <=) here: http://www.erlang.org/doc/reference_manual/expressions.html#id198443

The D programming language and DMC's extension to C and C++ did support these operators (all 14 combinations of them), but interestingly, D is going to deprecate these operators, mainly because

1. what exactly is a !< b? It is a>=b || isNaN(a) || isNaN(b). !< is not the same as >=, because NaN !< NaN is true while NaN >= NaN is false. IEEE 754 is hard to master, so using a !< b to will just cause confusion over NaN handling — you can search for such operators in Phobos (D's standard library), and quite a number of use has comments beside it to remind the readers NaN is involved,
2. therefore, few people will use it, even if such operators exist like in D,
3. and one have to define 8 more tokens for these seldomly used operators, which complicates the compiler for little benefit,
4. and without those operators, one could still use the equivalent !(a < b), or if one likes to be explicit, a >= b || isNaN(a) || isNaN(b), and they are easier to read.

Besides, the relations (≮, ≯, ≰, ≱) are seldomly seen in basic math, unlike != (≠) or >= (≥), so it's hard to understand for many people.

These are probably also the reasons why most languages do not support them.