We keep track of SMW tasks and roadmap items on GitHub.
Tasks with the "easy" label can be taken up by developers with little or no SMW experience without much effort. They are either really easy, or otherwise self contained and solvable without much SMW knowledge. If you're interested in helping SMW users, and/or becoming more involved in SMW development, by taking on such a project, and you have any questions, feel free to write about it to the mailing list or ask questions on the issue tracer itself.
There are a number of SMW tasks on WMF Phabricator due to legacy reasons. Please do not open new issues on Phabricator, and use our GitHub issue tracker instead.
From January 10 to 28, 2013, the SMW Project ran a short online survey of the community, asking mostly about priorities for future development of Semantic MediaWiki and related extensions.