user3775: On block explorer there are some address with public key available, and some without.
(e.g. this one has public key: 
http://blockexplorer.com/address/1HBheYzvX7NDtcwVrMS7gxReNRVezYS7w2 ,
and this one doesn't:
http://blockexplorer.com/address/1111111111111111111114oLvT2)
Why is that?
Is it because one has money sent out and one doesn't?
If I understand correctly then the public key is included in the transaction out of an address, is that right?

user153: The 1111111111111111111114oLvT2 hasn't been spent yet whereas 1HBheYzvX7NDtcwVrMS7gxReNRVezYS7w2 has.
To spend, the public key is part of the INPUT's ScriptSig:

http://en.bitcoin.it/wiki/Transactions#Explanation

So until there is a spend transaction, the public key isn't known to the network, just the Bitcoin address.
Related: Why is it impossible to derive public key from address?

3775: <p>On block explorer there are some address with public key available, and some without.</p>

<p>(e.g. this one has public key: </p>

<p><a href="http://blockexplorer.com/address/1HBheYzvX7NDtcwVrMS7gxReNRVezYS7w2" rel="nofollow">http://blockexplorer.com/address/1HBheYzvX7NDtcwVrMS7gxReNRVezYS7w2</a> ,</p>

<p>and this one doesn't:</p>

<p><a href="http://blockexplorer.com/address/1111111111111111111114oLvT2" rel="nofollow">http://blockexplorer.com/address/1111111111111111111114oLvT2</a>)</p>

<p>Why is that?</p>

<p>Is it because one has money sent out and one doesn't?</p>

<p>If I understand correctly then the public key is included in the transaction out of an address, is that right?</p>
 153: <p>The 1111111111111111111114oLvT2 hasn't been spent yet whereas 1HBheYzvX7NDtcwVrMS7gxReNRVezYS7w2 has.</p>

<p>To spend, the public key is part of the INPUT's ScriptSig:</p>

<ul>
<li><a href="http://en.bitcoin.it/wiki/Transactions#Explanation" rel="nofollow noreferrer">http://en.bitcoin.it/wiki/Transactions#Explanation</a></li>
</ul>

<p>So until there is a spend transaction, the public key isn't known to the network, just the Bitcoin address.</p>

<p>Related: <a href="https://bitcoin.stackexchange.com/questions/7683">Why is it impossible to derive public key from address?</a></p>
