Can superuser's reputation be synchronized between the sum of SO, SF plus any SU rep? Just an idea.
This I could actually see happening, as opposed to moving rep over from SF to SO and vice versa. If you are intelligent enough to rack up massive reputation on SO and SF, you could theoretically be seen as a knowledgeable enough person to have high rep on SuperUser.
Plus, with the hordes of noise that is inevitable on that site it may be a good idea to have a lot of high-level users there to help clean it up immediately.
Another idea, which may be easier to swallow for some of the masses...just make it a one time synch. When you join SuperUser your rep is initially set to your total from SF and SO, but it wouldn't grow along with your other rep if you don't put in the effort on SuperUser
Edit: mmyers brought up a nice idea about capping the initial rep score at 10,000 if there was a one time rep score set to your SO + SF reputation. This would allow us to still start on a fairly level ground with the really big reputation scores that are already present on SO.
I think that would be a mistake as it would stop people who could make a big contribution to the site from feeling the need to do so. People who want rep on SU should contribute to SU to get it. Quality answers on SU from the guru's at SO and SF will help SU grow more quickly as it proves itself to be a great resource to people asking the questions.
Interesting thought - is it because you think the site will need a large number of users with administrator level access?
Even though this question is now closed I thought I'd add the idea I had this morning.
Rather than give a large rep bonus to people to access the admin functions - make them admins, at least temporary admins. Open up (self) nominations and then if there's more than the desired number hold a vote. The winners get admin (>10K rep) rights on SU.
Then either after M months and/or when N users have >10K rep these rights are removed from those users who still have less than 10K rep.
This gives us (the community) the number of admins needed for the new site but doesn't put people off when then go there and see some people with huge rep scores.
If the sites are truly designed to cover separate topics, then the reputation you garner on SO and SF should not matter. If you are incredible at one of them, you should be able to do well on SU, but it's not guaranteed.
I know people who are phenomenal programmers, but have no idea how to get the printer to stop blinking. A similar argument goes for someone who may be able to build a server from scratch, but wouldn't necessarily know how to change the colour of alternating excel spreadsheet rows.
The target of SO is "Programmers" The target of SF is "Hardware/Server Administrators" The target of SU is "end users / anyone"
And I, for one, think that Jon Skeet is NOT the best representative of a 'typical user'.