Select multiple photos from camera roll iPad2

After navigating to the folder that has the pictures that you want to email, Tap on the arrow icon in the upper right corner of the photos app, select up to 5 photos at a time by tapping on them - and then tap on Share in the upper left and select email

This is covered on page 126-127 of the "iPad User Guide for iOS 5.1" which is a handy guide to have in iBooks on the iPad. From the thumbnail veiw tap the share button then sellect a maximum of 5 photos. The 5 photo max may also be limited to an attatchment file size by email service providers on either end.