I’ve been looking at job postings lately and have had a few chuckles when I see problems with compound adjectives, whether hyphenatedor solid. [To get technical, it's an adjectival phrase. The links do a great job describing the proper usage.]
The specific copy got to me today was a description of responsibilities. The sentence read “Work with cross functional and virtual teams.” What it says is that the teams are annoyed, but organized in functional and virtual teams; it is unclear if the virtual teams are cross.
Simply stated, this makes much more sense with a hyphenated compound word, cross-functional. I’d be much happier working with a team like this: “Work with cross-functional and virtual teams.”