Firstly let me thank you guys for your previous advice on linking.
I launched mynewwebsite.co.uk on Monday and was listed by Google at no. 9 on Wednesday. I didn't include any reciprocal links, just one-way links via free directories, articles, forums and a couple of links from friendly PR3/4 sites.

From what I have seen and read, Google.com favours dotcom sites and Google.co.uk favours dotcodotuk sites.

My question is this:
If I just point mynewwebsite.com at mynewwebsite.co.uk will it get the same ranking (page position, not PR) on Google.com as it does on Google.co.uk?

I gather that if I create an identical mynewwebsite.com site and host it separately I could be penalised for having a mirror site - is there a good way to equalise the search engine rankings for mynewwebsite.com and mynewwebsite.co.uk?

" If I just point mynewwebsite.com at mynewwebsite.co.uk will it get the same ranking (page position, not PR) on Google.com as it does on Google.co.uk? "


No...You will not get same ranking as that of .co.uk;
For ranking better at UK search engine you need 2 main things
*) .co.uk or uk.com domain name( cctld)
*) Try to get a UK host who have their server in UK ( Geographical location of server matters in ranking )
Also try to get as many as UK backlinks as possible all from relevant sites if you want to rank well in UK.

I think you can easily rank better for UK SE if you have UK cctld and UK Hosting.