Thank god someone erased Granada's previous comment. He needs to be reigned in.
Granada, this is not your personal forum to spout your views on sexism, racism, or any other hatred.
The fact is, while BA may sell itself as a great Gay destination, the reality is that the scene is still pretty underground. I'm from Vancouver so to me it's kind of strange -- the absence of "other" in this city (other race, other sexuality etc -- Capital can come off as pretty conformist). This definitely is not the Castro nor the West End.
On the other hand, there is the right to Civil Union and homosexual couples that take advantage of this are guaranteed the same rights as any married couple. The Civil Union document however is not accepted outside of Argentina, I believe -- ie if you're Canadian and move home you would have to get married there as well to have it recognised.
In areas like San Telmo and Palermo, affection between a same-sex couple would barely raise eyebrows. However, the gay couples I know never even hold hands in public -- now that could say just as much about them as it does about the city, but I don't want to get into their own psychology!
One couple I know just went to Salta last week -- it took them awhile to explain to the guy that they only wanted one room and they only wanted one bed in it. This was not a language issue -- they are Argentine -- this was essentially an initiation for the hotel owner into the world of homosexual travel!
There are definitely areas where you'd want to be careful in the city, there have been incidents of gay-bashing in the past.
A new gay-only restaurant just opened last week in Palermo, so the scene certainly is growing and becoming more open (or since it's a private resto, would that be more closed, ha!).
It can be kind of funny here -- the portenos totally accept transvestites on primetime tv, but only the good-looking ones! On bailando por un sueno there are two -- Florencia de la V, who everyone loves, and then there's another not so good-looking girl who's name I can't remember that people can't believe -- in fact the guy that's dancing with her is supposedly paid twice as much as everyone else to do so. Florencia de la V is treated completely differently in this respect.
In terms of the pick-up scene beyond the clubs, there's definitely a lot of park life going on, and lots of dating/escort services as well.