This big news was just announced last week by Matt Cutts from Google; that Google Places will now show your on customer reviews posted on your own website if they have been coded with Rich Snippets Reviews code. You can read the full FAQ section from Google on this topic and other questions, but for most of us this is huge news.
The big key here is that your testimonials and services reviews residing on your own website have to be coded properly with the hReview Rich Snippet code to be picked up. If it is coded properly Google Maps now known as Google Places will eventually place all these reviews, without additional intervention from you, on your Google Places page.
As reviews you may have solicited may be powerful and focused on your services offerings and will typically be favorable, or you would not have posted them yourself, this is a huge boon to every business that wants to build reviews to achieve better organic Google Maps or Google Places placement.
See the sample code here under the section microformats: http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=146645
Here is exactly what Google says on this topic:
How will Google treat businesses posting testimonials with review mark up on their own site? Will these be treated as a review by the Place Page?
Testimonials will be treated as business reviews on the Place Page.
If I annotate my site with structured markup, how fast may results appear on the Place Page?
It typically has the potential of appearing within a couple of weeks of your page being indexed by Google. Currently we will only be able to recognize basic business listing information (name, address, phone number) and surface reviews and photos.
If you have not coded your testimonials, now is the time to review that you have them coded in a format that will help you with Google Places.