Usually the books have the same advice, it's just that the publishers have been updated. It would be fine to purchase the 2009 edition so long as you be sure to visit the website of the group that you're sending your poetry to. They might have gone out of business in a year or changed their submissions guidelines or discontinued a competition or changed what they're actively looking for at present. So, whether you get the 2009 version or the 2010 version, be sure to visit their website. You shouldn't have any problems if you do.
If you are worried about the change however, you can always go to your local library and get the current edition. They often have them in stock. You might not be able to check it out, but you can get what you need while you're there.
I hope that this helps. As I said, you can purchase the 2009 edition because they're really expensive, and be sure to read books from whoever you're sending to and be sure to scan their website thoroughly. If you're going to invest in the 2010 edition, you should buy Writer's Market instead- it's larger and includes more houses.
Good luck and happy writing!
If you are worried about the change however, you can always go to your local library and get the current edition. They often have them in stock. You might not be able to check it out, but you can get what you need while you're there.
I hope that this helps. As I said, you can purchase the 2009 edition because they're really expensive, and be sure to read books from whoever you're sending to and be sure to scan their website thoroughly. If you're going to invest in the 2010 edition, you should buy Writer's Market instead- it's larger and includes more houses.
Good luck and happy writing!