The final of the Eurovision Song Contest 2015 will indeed be held on Saturday the 23rd of May 2015. Austrian broadcaster ORF has announced the official date, with the two semifinals being held on Tuesday the 19th of May and Thursday the 21st of May.
ESC Daily posted some weeks ago that it was most likely that the preliminary dates for the contest in 2015 were about to change. This news has now been officially confirmed by the EBU.
The host city for the 2015 contest will be made public within the next two weeks. Vienna, Innsbruck and Graz are still in the running. The Stadthalle in Vienna (picture in this post) seems to have the best papers.