Looks like Leycesteria formosa (Himalayan Honeysuckle) one of my favorites.
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My neighbor informed me that this plant was on the invasive list. I love it also and have not had it seed in my garden.
Does anyone have experience with it becoming a problem in a Seattle garden? I have been able to propagate it but don't want to cause problems in other gardens if I share it.

It is listed as an invasive species in Australia and New Zealand, but then a great many plants native or common to other parts of the world (and very well-behaved in their place) tend to be invasive in these countries. Location is everything when it comes to invasive properies so there must be something about a very benign climate and lack of natural competition or predators in Oz and NZ :-) At any rate, it is not listed as invasive anywhere within the continental US and in fact is not hardy in much of this country. I've seen mature stands of this in various gardens throughout the area and reseeding does not seem to be a problem.

I've had this in my garden since the the 80's in a couple of different locations, 2 years ago I found a lone seedling which my neighbor quickly found a new home for in his garden. Not invasive here in the least.
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Thanks gardengal48! This is the same neighbor who also said as she looked at the begonias under the flowering cherry - 'you certainly have a lot of different colors'. 'Yep' I said, 'I tried to get every one!'
I really had to laugh - that is the point of the little garden area in memory of my dad who loved begonias. Now I can pot of one for my sister and niece. They both have asked for a start of this plant.

At least she isn't reaching over the fence and cutting your plants. I cannot make the same claim.