Just found a cool tip to aviod default page zoom in iPhone . Just add the following tag
<meta name=”viewport” content=”width=320; initial-scale=1.0; maximum-scale=1.0; user-scalable=0;”/>
on further dig I found some useful apple development guides describes about the iphone viewport and customizing style-sheets
http://developer.apple.com/iphone/library/documentation/AppleApplications/Reference/SafariWebContent/UsingtheViewport/UsingtheViewport.html
http://developer.apple.com/iphone/library/documentation/AppleApplications/Reference/SafariWebContent/AdjustingtheTextSize/AdjustingtheTextSize.html
