jeffatrackaid - 9:19 pm on Feb 11, 2010 (gmt 0)
Our team moves servers for people almost every week and the honest answer about SERPS:
You never know.
There are reports that bad IP neighborhoods can negatively impact SERPs. This can work both ways. If you are in a bad area and go to a good one, you can get a boost.
This must be handled very smoothly and correctly. TTLs need to be lowered well in advance of the actually migration date.
If possible, you will want to leave the old server online for 2-4 weeks. I have seen Yahoo's bot visit the old IP for up to a month after changing DNS. If you pull the old server down too soon, the bot may think your site is gone.