As an educator, my favourite, regular destination has been the International School's Island. The island was set up by @shamblesguru and is designed to support mainly k-12 educators with their ongoing professional development challenges. One of the the most popular areas on the island is the three Towers - Curriculum, Information, Technology. In these towers is a growing index of education places in Second Life and probably the most comprehensive collection of education links in Second Life itself [1. International Schools Island]. As well as finding huge amounts of useful information to enhance my CPD, I have attended seminars in the Mountain top retreat and engaged in discussions with other educators.
Second Life for Education is huge and there are numerous opportunities to use it in your educational life. I would suggest going and and having a look at some of the resources i have linked to above. The following will give you a few more ideas... Enjoy your journey :)