Whats new in 4.6.1

It depends from which version you upgrade.

If you upgrade from 4.6.0 then it's enough to just overwrite the files.

If you upgrade from older versions please see:
www.sakic.net/news/sef_advance_4.6_released/
www.sakic.net/news/sef_advance_4.5_released/

What little extras did you give us

How about your latest version 4.6.2 ?
I'm using right now 4.6.1.
Can I just overwrite the files in this case?

How about your latest version 4.6.2 ?
I'm using right now 4.6.1.
Can I just overwrite the files in this case?

Yes.

What little extras did you give us

4.6.2
+ Fixed a bug with determination of Itemid
  when category directly linked to menu in a paged category view

4.6.1
+ Added index to alias table
  ALTER TABLE `jos_sef_alias` ADD INDEX(`published`);

Minor updates only contain bug / problem fixes, not new features.

I suppose updating from 4.6.2 to 4.6.3 is also by just replacing the changed files?