[seanmcdirmid]

It depends on what region you are in. Guy in the UK I think means male as in Guy Fawkes. In the USA, Guy is often genderless except in the south where gal can be used without being very awkward. In general, you should just steer clear of the word, however, as opinions about it are diverse.

[Silhouette]

Guy isn't necessarily male in the UK, except when used as a name and maybe in the context of "guys and girls". "Hi guys" is a common greeting here when addressing a mixed group.

[OJFord]

> Guy in the UK I think means male as in Guy Fawkes.

That's a name. Nobody's going to think you're only talking about men named 'Guy'. Context is king (ooor queen!) - it can certainly be either alone, or mixed.

[seanmcdirmid]

http://www.word-detective.com/2009/08/guy/