Which organisms have introns?
As a general rule, a blanket statement in Biology should always be considered false.

It so happens that bacteria do have 'introns' (or at least the intron genomic sequence has been determined) in the sense of the cis-acting autocatalytic Group I and II introns. These are sequences of RNA that adopt such a conformation to catalyze their own excision from an mRNA transcript, and thus may be considered ribozymes, enzyme made of ribonucleic acid.

Although not generally considered 'introns' segments of RNA are removed during the course of tRNA in both prokaryotes and eukaryotes.

Now introns that are removed by the action of the spliceosome are strictly found in eukaryotes, as bacteria lack the spliceosome.

There seem to be a considerable number of papers regarding the question of intron (particularly spliceosomal) phylogeny that should be relatively easy to find if you are so interested.

One example paper in which viral introns (Group I) are reported:
http://nar.oxfordjournals.org/content/22/13/2532.abstract