Back in September, I wrote a post about how sometimes the "easiest" terms seem to be the hardest ones to translate, at least when it comes to Spanish to English translations. One of my main examples focused on the ambiguity of certain nouns used in relation to family members, such as hijos, padres, and hermanos. Without additional information, a translator has no way of knowing whether these three words are being used to refer only to males (sons, fathers, brothers) or if they are referring to people of various genders (children, parents, siblings).
While it would be lovely if languages like Spanish simply stopped using grammatical gender designations for their nouns, it seems pretty unlikely that such a huge linguistic change will ever take place. That leaves us with two options: either come up with a solution for these ambiguous examples, or just live with it.
One solution that has become increasingly popular in informal Spanish communication, especially online, is to use the at sign (@) when referring to a group of people that includes both females and males. For example, if you want to use a gender-neutral term to refer to a group of friends, you can call them your amig@s. Not only does this avoid the ambiguity of using the masculine plural ending -os for mixed groups from the equation, but the symbol also somewhat resembles an o and an a, which are the masculine and feminine noun endings in Spanish.
That said, while the arroba, as the symbol is called in Spanish, is frequently seen online, it certainly hasn't become standard practice. First of all, there's just the fact that using @ as a letter seems very informal, and indeed even "wrong" to some people, likely because it is so unusual and new. It also doesn't necessarily solve this issue when it comes to spoken language, since there is no widely accepted pronunciation for the at symbol. However, there have been some proposals for phonemes that @ could represent.
In any case, if you want to stick with recommendations of the Real Academia Española, the regulatory body in charge of the Spanish language, then you won't want to start writing words like amig@s, herman@s, or even bienvenid@s. Its Diccionario panhispánico de dudas, which addresses questions related to the use of the Spanish language, points out in its entry on gender that the arroba is not a linguistic sign, and that its use in such situations could lead to further grammatical inconsistencies, as in the example "Día del nin@", in which the "el" in the contraction "del" would only apply to the masculine half of "nin@".
Clearly this linguistic issue hasn't been solved, but at least people are thinking about it! Languages are living things that are meant to evolve over time, so hopefully one day someone will come up with a lasting solution that everyone, including the Real Academia Española, can agree on.