Using Google Site Search - Any Implications for SEM?

I've never seen a Google Site Search have any effect on organic rankings - neither positive or negative.

I second that. If you modify the HTML of your pages then, of course, there's the potential for some impact (almost certainly slight, depending on how you go about it). Google site search is retrieving content from the Google index - that is built elsewhere. It's just a fancy interface to site: searches basically.

I also agree that site search should not affect your organic rankings.

The only negative effect I might foresee would be if you linked to Google serps pages in an attempt to get those serps pages indexed. That's something Google doesn't like. Otherwise, there should be no problems.

Thanks Chaps

Am I understanding this correctly:

Site Search will 'index' and return results purely from your local site (or certain directories if you specify this), but these pages will still be held in the 'worldwide' Google database? Is the algo used to return Site Search pages to local SERPS the same as the global Google algo - therefore to get the best quality results you should optimise these pages as you would for overt Google organic marketing?

If you are asking for a whole load of pages to be spidered specifically via Site Search and they are contained in a 'generic' database which provides all SERPS regardless of the location to which they are published (local or wordwide organic), would this not have an effect on a sites' organic positions overall?

Or, are Site Search pages somehow 'ringfenced' for publishing to your local SERPS only?

Sorry for so many questions.