I got stuck on this question while I was wondering if I could use one of the graphs from the PHP Eats Ruby article to illustrate the Ohloh listing on Wikipedia. I then realised that the content of that article is (c) Ohloh so the graphs could not be used as such on Wikipedia.
Whence the question: under what terms/license are Ohloh's data released, when not explicitly stated? This applies to the content of the website, the widgets and the data accessible via the API. The FAQ do not make any reference to license/term of use of Ohloh's data.
Lacking explicit license information other than the vague attribution requirement mentioned in the API's terms of use, it is hard to determine what kind of use of your data is legitimate and what would be a copyright infringement. Please make terms of use/license explicit and in case you opt for some common content license consider adding license metadata within your website header.
(Oh and on a side note, apologies if this has already been discussed somewhere but I couldn't search the forum.