There is only 6 months between filing date and issue date of us7445677 patent. Am I missing something?
Tarik - A few months ago I made the following histogram of patent application pendency for US patent applications. The chart is discussed on my blog. Pendency Discussion on Patently-O.
The basic answer is that the average pendency for an application is just over five years from the earliest priority filing and about 3 1/2 years if ignoring priority filings (such as provisional or parent applications). The USPTO reports an average pendency of 2.8 years by (1) ignoring priority claims and (2) counting the RCEs as new application filings. As the chart shows below, there is a large amount of variance and so it quite likely that any particular patent's pendency is far from the average.
The patent that you mention above (US7445677) did issue in only six months. In that case, the applicant had filed a petition for accelerated examination. A discussion of different ways to accelerate examination is available here: Discussion of Options for Accelerationg Examination