You may well have heard of Google's Protocol Buffers, the latest and trendiest way to treat everything as a nail. The logic goes something like this: XML is complicated, verbose, expensive to process and ubiquitous. So, let's use something completely different for everything instead!
What's XML good for? It's a decent representation of structured data. So, we get to use it as an insane way of writing RPC requests and obfuscating data better put in a CSV file. Oh, and serialising objects. This is all obviously rubbish, and Google's protocol buffers will solve everything. Until we realise the weaknesses of the new format, that is.
What might be nice is if people actually applied sensible tools for the job, and didn't conflate different requirements. Protocol buffers are a lightweight IDL implementation, so it's probably best to use it for that. Use it to generate RPC requests. Maybe use it for inter-language communication of data-structures, and limited persistence.
Then notice that protocol buffers aren't self-describing, aren't easily human readable or editable, and things like that. Note that you might want to use JSON or even XML for appropriate situations. CSV maybe. And notice that object serialisation (as opposed to data structure serialisation) is something you don't want to conflate with other stuff, because if you do it'll become some kind of interface, and if you're really unlucky people will be editing the serialised structures by hand, and it's all a mess.
Please. Use the right tool for the job.