If you really want some good info about owning and caring for an octopus I recommend going to this page:
http://www.thecephalopodpage.org/">http://www.thecephalopodpage.org/</a>
Escaping is not the only issue, you must also be prepared for them inking the tank(toxic) and removing it. Because of this, they commonly do not ship well, as they will ink the bag and then sit in it during shipping. They are also commonly expensive in pet stores and with out knowing their age, senescence could be right around the corner, as many species that are common to pet stores have short life spans. I have always wanted one, but until I live near the ocean and can collect them myself, I can only dream. As far as intelligence goes, you should check out this video on the [I]Thaumoctopus mimicus</em>.
[IMG]http://www.youtube.com/watch?v=t-LTWFnGmeg&feature=related">http://www.youtube.com/watch?v=t-LTWFnGmeg&feature=related</a>