it something happened with gmail today - I just cant access my account there for regular communication. Beeing annoyed with that I started to serch for answer on my quastion then I found soon the reply of Ben Treynor, Gmail's VP of Engineering and "site reliability czar," who said the blackout was actually a result of recent changes meant to improve service.
So, Ben Treynor wrote in his blog: "This morning (Pacific Time) we took a small fraction of Gmail's servers offline to perform routine upgrades. This isn't in itself a problem -- we do this all the time, and Gmail's web interface runs in many locations and just sends traffic to other locations when one is offline.
However, as we now know, we had slightly underestimated the load which some recent changes (ironically, some designed to improve service availability) placed on the request routers -- servers which direct web queries to the appropriate Gmail server for response. At about 12:30 pm Pacific a few of the request routers became overloaded and in effect told the rest of the system 'stop sending us traffic, we're too slow!'. This transferred the load onto the remaining request routers, causing a few more of them to also become overloaded, and within minutes nearly all of the request routers were overloaded. As a result, people couldn't access Gmail via the web interface because their requests couldn't be routed to a Gmail server."