It's referred to as the pipe and it's one of the characters Google ignores. Google actually ignores most characters except for when it's smart enough to know it's essential to what you're searching for, like say "c++" if you're looking for stuff related to that programming language. Google also ignores "stop words". You can look up a list of them but basically they are common words that add no value to the search, like and/in/on etc. The general advice is to always write for humans first, SEO second, so you don't want just a string of unpunctuated keywords or keywords separated by a pipe for better human readability. But if you know that Google ignores most punctuation, special characters, and stop words, you can write content in human-speak that still incorporates long-tail phrases if you were to cross-out all the parts Google doesn't recognize. And since Google doesn't care about grammar or periods, the words at the end of a human-speak sentence connect to the words at the beginning of the next sentence, creating long-tail phrases same as if you made them intentionally. And this is one thing I know for sure is the same with Zazzle's search.
We tend to think of our tags as 10 tags of 5 word each and try to do the best we can making long-tail/exact phrases out of 5 words. But Z see's it as one long unbroken string of 50 words. So for simple example if you wrote these tags
bright yellow, sunflower, field of wild flowers, illustration by windy
then "yellow sunflower", "sunflower field", and "flower illustration"
also become long-tail/exact phrases. Coming up with tags is time-consuming enough as it is but if you go the extra mile to arrange them in an order that creates more long-tails likely to be searched you can get more bang for your buck out of your allotted tag words.
Back to punctuation. I name all my designs and use that [Design Name] in brackets in my product titles, and then use that design name for my collections. One of my design names had an ampersand in it ("Fire & Ice"). As far as I know that didn't effect search, but because & is a reserved character in coding, it caused some hiccups. Using the share code to post something to the forums, the entity name (&) would show instead of the symbol. Also that & posed an issue for pulling the collection in Nifty, I remember talking to Mark about it but it was along time ago so I don't remember (sorry, Mark!) if he created a work-around for that or not as my solution was just to do away with the & and use and instead. Oh, and as far as I've been able to tell, the brackets in my titles's haven't effected searching either .
