According to http://drupal.org/node/252241 a revision author token may be available. However I do not see anything referencing revision:author (variation?) in my list of available tokens. Is there something like this?
For D7, in order to gain access to revision:author tokens, you have to install Revisioning module. (of course you also need token module)
Then you can see all the available tokens by going to Help -> Token (/admin/help/token)
So after enabling the module, a new token category, named "Revisions", is available. You can see for example [revision:revision-author] which refers to "The author (or editor) of the revision" and a bunch of others regarding the revision author.
P.S. As per this there seems to be currently a bug regarding [revision:revision-author:mail]
Good luck and let me know if you need more help!
This one is for D6 but probably give you a hint: http://api.drupalhelp.net/api/revisioning/revisioning_tokens.inc/6.4
Have you tried Custom Tokens module ?
It gives the user the ability to create custom tokens for specific replacements that can improve other modules relying on the Drupal 7 token API or, for Drupal 6, the Token module.
Versions 7.x-1.x and previours relied on PHP evaluation to build custom tokens.
The idea is to define your own tokens and use them. Also it works with PHP Filter Module.
Install module goto
admin/structure/token-custom/add to add a new token. Since you want to get the author from node submission select Token type node
When I use tokens together with Rules action "After updating existing content" this token gives me the author of the updated node (i.e. the author of the latest revision): [site:current-user]. (To get an author of the first revision, you can use [node:author].)