I just got back from a two-week vacation, returning to work the same day my younger cousin started school, so this feels like my “What I Did On My Summer Vacation” essay. But it really  should be titled “What Everyone Else Did On My Summer Vacation.”

I came back from meandering country drives and reading novels on my porch to find that Dow Jones Indexes is up for sale, commodities ETFs are confronting a sizeable speed bump, and John Hancock has joined the ranks of mutual fund providers seeking entry into the ETF market. (See related story here.)

Okay, I know I’m a bit of a slacker (who spent half of her vacation rediscovering the joy of sleeping in), but isn’t summertime supposed to be when things get slow?

I seem to remember the summer of 2008 as being one long snooze, though I guess the autumn kind of made up for the summer boredom quite nicely, in a cataclysmic kind of way.

And it’s not just the last two weeks. I kind of feel like I was on a bullet train and didn’t realize how fast it was going until I got off at one of the stops. The whole summer has been pretty crazy in ETF-land.

It kicked off with BlackRock’s acquisition of Barclays Global Investors and the iShares, which was officially announced in June. Boom. In one fell swoop the entire competitive landscape of the ETF market was reshaped. We just don’t know how yet.

But it’s also been undergoing a much slower evolution from the other end. Pimco made its ETF debut in June, and the summer saw a bunch of filings from other well-known mutual fund firms that are looking to become ETF providers. The most notable of course is Schwab, which made its first registration filing in July, with Old Mutual close behind, and now John Hancock has filed a 40-APP. Jefferies Asset Management, a subsidiary of Jefferies Group and another relatively big name, has also filed a 40-APP for ETFs recently. (See story here.)

And then of course there’s leveraged and inverse ETFs. 2008 was really their year, with Direxion bursting upon the scene with triple-exposure funds. According to the NSX, assets in such funds were down at the end of July from May, but remain at more than $30 billion. However, at the same time assets were declining, new products regularly were hitting the market, with ProShares alone launching 13 new funds since the end of May, among them its first triple-exposure ETFs, which are tied to the S&P 500.

But let’s not forget FINRA’s fatwa early on this summer, which cast a temporary pall over geared ETFs. In June, the regulatory organization issued a statement saying that advisers were essentially failing in their fiduciary duty if they advised clients to hold leveraged or inverse ETFs for more than one trading day. Not surprisingly, the blanket statement caused a bit of an uproar, and by July FINRA had backpedaled quite a bit. It now holds the stance that investments in such funds should be monitored closely and that holding periods longer than a single trading day can sometimes be appropriate.

The summer was also big for commodities ETFs – in good ways and bad ways. An unprecedented number of exchange-traded products –two ETFs and two ETNs – halted creations this summer, the most recent being the iShares’ GSG, which tracks the S&P GSCI. Given that the SEC is considering placing limits on how much funds can invest in individual commodities, more funds are likely to follow suit, unless a resolution is reached soon. Halting share creations has the effect of turning an ETF into something that behaves more like closed-end funds, which often deviate from their NAVs.

Yet this summer also saw the entry of Europe’s ETF Securities into the U.S. market with its ETFS Silver Trust (NYSE: SIVR); the firm is known as a major player in commodities ETFs throughout Europe, and its penetration into the U.S. (with at least three more filings in the wings) indicates there could be a marked expansion in commodities ETF here. SIVR itself has made a big splash, attracting $100 million in assets with just one month’s worth of trading under its belt. Given that ETFS is relatively unknown in the U.S. as a brand, SIVR’s price point of 30 basis points probably has a lot to do with its success , as it severely undercuts the iShares Silver Trust’s (NYSE Arca: SLV) 50-basis-point expense ratio.

So if we’re just winding up the summer “downtime,” I’m kind of wondering what’s in store as autumn looms. Considering all the new developments and unresolved cliffhangers, it could be pretty interesting.