Why not interlinking same thematic sites?

The cross linking penalty fear

[silverbytes]

I have some websites about same general topic. I've readed some post that encourages to avoid interlinking in order to be safe from Google penalties. I wonder why not interlinking those websites: they are real content sites and users might be interested in going from one website to another. The banners area (present in all pages) might contain the banners to other websites (3 websites actually).

However I feel like doing that is suicide reading other posts, but I don't find a reasonable explanation other that "Google may punish".

[DoingItWell]

If you're that worried, why not put rel="nofollow" on the links and be safe?

Edited: Added missing quote.

[graeme_p]

I ahve two related sites (lets call them "widget news" and "widget background info") that are heavilly interlinked.

There are plenty of sites that are interlinked for good reasons (company's in the same group, colleges of a university, magazines from the same publisher) so I doubt that Google would make the interlink penalty too strong (more likely they will merely reduce the benefit of those links, a suggestion I have seen of WW before).

[mirrornl]

you will be ok linking those pages to each other

[nippi]

i link the #*$! out of my related sites.

never had a problem

[phantombookman]

I cross link all my sites.
Stands to reason you would use one front you own to promote another.

Works incredibly well for me.
I put links where they would logically be though.
No site-wides etc

[silverbytes]

I though putting graphical banners, on banners section and text link at bottom page on page's foot. In fact they receive traffic coming from those interlinked actually, perhaps the penalty is a mith.