Wonderful flower, isn't it? That is Lonicera periclymenum Serotina or "Late Dutch Honeysuckle". The year 2002 was the first year it flowered and it truly surprised us with both the profusion of flowers and the period we had flowers: from late May/early June until late August at time of writing and they show no signs of letting up.
As nice as the individual flower is though, it is the overall effect of the flowering vine with it's cascading layers of flowers that make it such a sight. The flowers are fragrant, but since their flowering period overlaps the flowering period of our Oriental Hybrid Lilies there is a period of about 6 weeks or so where you cannot smell them much in our yard since they're being overpowered by the nearby lilies.
The other Honeysuckle we have is a Lonicera Japonica Halliana, much smaller in flower, but a more vigorous grower than the other one. It proved to be rather susceptible to mildew and that forced us to drastic action: prune! Severely! It's coming back nicely at the moment but we'll have to wait and see if we continue to get the same problem again next year. The action may be even more severe at that point.
In spring 2003 it did the same thing and radical measures were taken in mid May: it's outta here! The corner it occupied has now received a seedling from the other honeysuckle, less variety, but a more reliable grower that doesn't suffer the mildew problems of the other.
This is the beginning of the flowering period in early June (above) and it looks good, but it's nothing compared to the clusters you get in late July and August (below).