I heard with the new google algorithm update (Jagger), same link text anchor makes a site less important. So it is better to use different texts anchors for links to your site.
i heard it other way around people who had consistently used the primary keywords for anchors matching back to right webpages did better. as always if all links to your site has the same anchor text it is going to look like you tailored those links and not organic...
ya it's quiet true.. Anchor text key-phrase could improve SERP. back link help to improve PR and anchor text help to improve SERP. example: Anchor text An Affordable and Professional Web Design Company This key-phrase Professional Web Design Company has good SERP in google. even this site not listed in dmoz.org, but this site have a lot one-way link. and also this key phrase not found in title and metatag.
I'm not convinced that "same anchor text" has ever been an issue with Google or any other search engine. That said, it's still a good idea to vary anchor text somewhat - not to avoid a "penalty" but because it's a good idea to try to optimize for more than one relevant search term.