I have found a SEO which maintains sites related to hotels in main cities in Europe. This SEO placed about 8 links to my site and I respectively to SEO's 8 domains.
All of these 8 sites have different domains and link pages with PR 4-5. The thing is that they all have the same IP address. In addition to 8 they are offering more links from other domains, but again with the same IP address.
You raise an interesing point. I seem to remember reading that these links may be worth a lot less being all from the same source. Also, it could be regarded as too much of a link community which could be damaging.
The important issue for spam penalties is who you link to. 7 links to the same ip is worrying, with them all linking back. You could block the spider on your links out ;) or just don't risk it...... I would drop them.
I don't think google has a problem with links within an ip address as long as the domains are seperate. I think the logic behind this goes that there are communities based on a single hosting account and although all the sites are seperate and maintained by seperate people they have the same ip address. It would be wrong for google to penalise this sort of link structure as the links are perfectly valid and not an act of spamming. I wouldn't worry about it as long as all the sites are significantly different to each other and it's not just a free for all cross linking mess.