We've been anxious to see Griffin's iPad version of FlexGrip ($30) in person since it was first announced, and here it is: a silicone rubber skin with distinctive rear ridges that have been designed to make the iPad easier to grip. A Sleep/Wake button protector is built into its top surface, with separate holes for the iPad's headphone port and microphone, plus a side hole for the volume and screen lock features, and bottom holes for the speaker…