Yup. His writer has described him as "ready and willing to do anything with a pulse."
This seems to be more a recent development, at least for the majority of the run. I've read the majority of Deadpool comics and, other than this running gag with gay baiting Spider Man, he seems to be 100% heterosexual. More recently, they did an issue where they implied he was being a queer with another voice in his head, who turned out to be Madcap, who had been stuck inside Deadpool for years, but Deadpool thought it was just his imagination, an insane voice in his dead. Beyond that, the worst he's done is sleep with a female hippo-looking alien. Like it looked like a hippo. She was really rich though.
The most recent issues, with the queer Madcap insinuation, seem to be attempting to turn Deadpool into a more X-Meny type of character. Which is to say, filled with teenage angst, politically correct and navel gazing.