In reference to the patent: US20080264895
Is this patent valid?
The cited document is a patent application, not a patent. To determine the status of a US application the best approach is to look it up in the US Public Pair site. Go to Pair, get past the CAPTCHA and then (for this application) select the "Document Number" option and enter "20080264895". If you do, you will find that this application is listed as: "Abandoned -- Failure to Respond to an Office Action" as of 02-13-2012. The application had received a "non-final rejection". Many if not most applications receive non-final rejections" so that, by itself isn't an indication that the application could never be granted. However, it looks like the applicant gave up on it. It is still possible for the applicant to resurrect the application, but I would seem at this point unlikely.
If you click on the "Image File Wrapper" tab, you can look at the communications between the applicant and the examiner. It would be useful to read the Non-Final Rejection document as this might point out prior art that could keep you from using the described invention. Please understand that I am not a lawyer and this is not legal advice.