Starting with version 10 (released in September 2011), Adobe has removed support of JPEG 2000 from its Photoshop Elements software. (The latest versions of Photoshop CS still support JPEG 2000.)
Removal of JPEG 2000 support means that most general (non-professional) users will be unable to view/read JP2s with (one of) the leading image editor(s) aimed at this audience. The fact that Adobe doesn't deem continued support worthwhile may also undermine confidence in the format's long-term viability. On a side note, in a 2007 blog entry Adobe's John Nack already questioned continuing Photoshop's JPEG 2000 support.
http://forums.adobe.com/message/4843673 - Discussion on Adobe forum.
Photoshop Elements 11 Release Notes (see 'Upgrade Notes' section with list of discontinued formats)
Adobe's John Nack on JPEG 2000 (2007)