Now we can this feature emulate with dblink, and there are patches in commitfest based on background workers, and emulation will be cheaper.
I had not noticed that "background session" proposal. That's definitely an interesting feature to have for some use cases. Dblink implies a new connection I think, pretty expensive. I wish that the proposal would be language independent, like DB2 simple AUTONOMOUS declaration on a function. It seems quite heavily linked to PL/pgSQL right now.
Maybe year ago here was a discussion about autonomous transaction design - Robert proposed transaction scope - some like 'BEGIN AUTONOMOUS", I proposed function level. The syntax is not pretty important - this functionality is interesting - mainly for loging to tables - but there are risks - it again border transactional| untransactional - autonomous transactions are "untransactional" from outer transaction perspective - so some unwanted artefacts or risks are possible there - and application design should to respect it.