We heard that it may be a while after submitting their app for admission into the Marketplace, but in just a few days time, the famous messenger client from Shape Services has hit the Marketplace for $9.99. The messaging works across multiple services (AIM, Facebook, Google Talk, ICQ, Jabber, MySpace, Skype and Yahoo! ) and keeps the Metro UI look and feel. Searching the Marketplace for IM+ doesn’t yet yield results, but you can use the following link to open your Zune PC software and download the app from there.
Update: As noted by Dagolara in the comments, if you search for “IM plus”, you will find the IM+ app at the bottom of the list.