When I went and visited the Adsense blog earlier this morning, I noticed there is a new amendment on the program policies. Originally, all Adsense publishers are allowed to display one link unit, and Google would ignore the rest of the code, even if you had implemented. But now, you are allowed to display three link units per page. That mean, from now on, you can have 3 Adsense for Content units, 3 link units, 2 search boxes and 2 referral units (per product).
Personally, I think one link unit is not enough, but three seems to be a little bit more. Anyway, I am glad to hear this great news. You should spare some time in redesigning the layout of the page, try to figure out whether there are places to accommodate one or two more link units, which is a good source of clicks, at least in my case.
Link unit enables you to explore more space in your website for Adsense revenue. Since it resembles the normal links in your site. There will be a higher tendency to get more clicks from your visitors. It is definitely worth to put more link units in your webpage. There is also an optimization tips for the placement of link units. You should locate it in close vicinity to the main navigation column, and blend it to look similar to your links. On the other hand, you can also locate it on top of your site, and thus visitors have more tendency to click on the link.
C. K. Li is a SEO and Adsense expert whose company is Hong Kong based. He starts to share the Adsense tips and secrets in his blog Da Gsense Code, and welcome all questions about Adsense. http://www.DaGsenseCodes.com