How to be sure that whole of block chain downloaded? I catch myself on the thought, that I don't know how to verify that block chain downloaded or not yet.

How exactly I can be sure that all is ok with bitcoind or altcoins?

E.g. "terracoind getinfo" brings: 

terracoind getinfo

{   
    "version" : 80002,
    "protocolversion" : 70001,
    "walletversion" : 60000,
    "balance" : 0.00000000,
    "blocks" : 142718,
    "timeoffset" : -6,
    "connections" : 8,
    "proxy" : "",
    "difficulty" : 13505.04606600,
    "testnet" : false,
    "keypoololdest" : 1380559952,
    "keypoolsize" : 101,
    "paytxfee" : 0.00000000,
    "errors" : ""
}


Or novacoind:

novacoind getinfo             

{   
    "version" : "v0.4.4.5-2-gde717f9-dirty-beta",
    "protocolversion" : 60010,
    "walletversion" : 60000,
    "balance" : 0.00000000,
    "newmint" : 0.00000000,
    "stake" : 0.00000000,
    "blocks" : 19043,
    "timeoffset" : -15,
    "moneysupply" : 384762.67195300,
    "connections" : 16,
    "proxy" : "",
    "ip" : "128.73.179.81",
    "difficulty" : 97.09844140,
    "testnet" : false,
    "keypoololdest" : 1380559917,
    "keypoolsize" : 101,
    "paytxfee" : 0.01000000,
    "errors" : ""
}


Here are 3 answers about bitcoind:

How to check Bitcoind block chain download progress level

And only about downloading side part block-chain info. Is it true, that nothing embedded into default bitcoind for that task?
You can either do a sanity check as also suggested in Anonymous' answer: The age of the last block shouldn't be more than a few minutes old (depending on the coin protocol), usually not more than twice the aimed .

The other option is to compare the id of the last block against one or several well connected websites which respectively would be your coin's blockexplorer.com or blockchain.info. If that website's latest block has the same block id as yours, it is reasonable to assume that you are up to date.