The dates and kick-off times for the quarter-final matches were also confirmed, with Munster and Leinster's respective last-eight clashes with the Ospreys and Harlequins to take place on Sunday, April 12.
The first quarter-final match drawn out of the drum was top seeds Cardiff Blues versus three-time champions Toulouse. The winners of that game will have 'home country advantage' in their semi-final against one of England's leading sides, Leicester Tigers or Bath.
The third quarter-final pairing out of the drum was Munster v Ospreys, handing the defending champions or the Welsh region 'home country advantage' in the last-four.
Should Munster prevail in April and Leinster manage to get the better of Harlequins in their quarter-final, the Irish provinces will go head-to-head in early May for a place in the May 23 decider in Edinburgh.
The prospect of an all-Irish semi-final is certainly a mouth-watering one but the venue for the game would throw up a conundrum.
Under competition rules, Munster would not be able to stage the semi-final at Thomond Park Stadium and with Lansdowne Road still in redevelopment and Croke Park currently only an option for international matches, Leinster's own home ground, the RDS, may be pressed into action.
Of course, Munster famously beat Leinster in a memorable 2006 semi-final at Lansdowne Road on their way to becoming European champions for the first time.
The RDS' current capacity stands at 18,500 although it could be bumped up to 20,000 to meet the minimum capacity requirements for a Heineken Cup semi-final.
The decision, if indeed both provinces win their quarter-final ties, rests ultimately with tournament organisers ERC who will select the semi-final venues.
2008/09 HEINEKEN CUP SEMI-FINAL DRAW:
(Seedings in brackets)
Cardiff Blues (1)/Toulouse (8) v Leicester Tigers (4)/Bath (5)
Munster (2)/Ospreys (7) v Harlequins (3)/Leinster (6)
* Fixtures will be played on the weekend of May 2 and 3
Cardiff Blues (1) v Toulouse (8) : Saturday, April 11, 3.30pm
Leicester Tigers (4) v Bath Rugby (5), Saturday, April 11, 6pm
Munster (2) v Ospreys (7), Sunday, April 12, 1pm
Harlequins (3) v Leinster (6), Sunday, April 12, 3.30pm
* All kick-offs local times