Christian Schaefer has a recent post pointing out a common frustration among developers of applications with NoSQL backends, specifically with Doctrine, MongoDB and PHP DateTime objects - timezone conflicts.
I really like Doctrines way of dealing with dates and times. Instead of passing timestamps around or strings with ISO date format it simply makes use of the PHP native type DateTime which provides all you really need to work with. PHPs interface to MongoDB however comes with its own MongoDate type which provides hardly any functionality compared to DateTime and it's not compatible with it. So what's the difference?
In some of the comments to the post, readers mention that the problem is bigger than just the tools used to work with the database, it's that databases usually don't care about timezones when working with date/time. There's also an interesting mention further down about the timezone support MongoDB does have and an example snippet ofo code that uses the support.