I would translate it as "café" or "market," as opposed to other areas of business-to-business websites that just deal with profiles and product listings or advertisements. I'd probably stick with "café" here, since it's a more general term for business professionals to talk, unless you know for certain that that portion of the website is for market listings/transactions only. I can also think of a few Web sites in English that use "Café" when they refer to connecting professionals. (For example, "Translator's Café," which is similar to ProZ.)

I usually see business-to-business abbreviations in the English-speaking world as "B2B" when they are not fully written out.