Even the BBC gets part of a language story right! (If you don't get why that's shocking, click here and search 'BBC'.) But of course I have a quibble:
Very often [Hispanics] switch between languages within a single sentence, or borrow English words and put them into Spanish, making a hybrid known as Spanglish.Every language borrows from others, and English is vastly more hybrid on that count than most 'Spanglish' I've heard. Codeswitching is another game -- it's real and it's important and striking linguistic behavior. For example, you can only really do it appropriately if you're really solid in both languages. But getting at that behavior is just not something you can usually ask people. Bilinguals are often aware that they codeswitch and may report it, but what the label means varies -- I've heard people who use an occasional English word consider that 'Spanglish', and everybody in this country does that, pretty much. In fact, I'll bet you $20 that there are systematic differences in what people mean by the term across generations.
Anyway, more information in easy-to-present form for how fast immigrants are learning English today.