It looks like Photobucket made a BIG change to their TOS on the 28th June and now the only pricing tier that allows 3rd party hosting (posting pics to a forum) is the $399 per year plan. As yet my account hasn't been flagged, probably as I don't have many pictures or much traffic but I'm sure it will be soon.
Photobucket has clearly made the decision that free accounts don't pay the bills and are essentially charging for cloud storage below the top tier plan, which actually provides 'normal' picture hosting options. I wouldn't be surprised to see a newcomer to the market gain a foothold in the void of photobuckets' departure as a viable free hosting option. I wouldn't hold my breath waiting for Photobucket to reverse their decision though.
For me, I guess the easiest (or rather cheapest) thing to do is host my pics on some of the hosting space I already pay for, for other reasons. I'd suggest maybe looking into a similar thing, either a free hosting site with a couple of gig of space, or a reasonably priced hosting plan and your own domain. Owning your own domain has the added advantage of guaranteeing permanent access to your email address even if you change employers, or ISP's.