Stuff in late 2008/early 2009 that felt core 2000s

MYSPACE, AOL AIM, pretty much what u said, SCENE was still holding on into the late Summer of 2009, Blockbuster Video, 106 & Park.
Mtv TRL was still on until Nov and then was replaced with On with Alexa Chung.

For some states the 2000s fashion trends held on longer, but in others Hipster came fast


WWE RAW still had its paparoach to be loved theme from 2006 and ended around 2009

Rock was still popular. Fall Out Boy's music video for "I Don't Care" (which was their then newest single) was promoted as a report on A Current Affair, Kings of Leon were the biggest name in music and there was a lot of hype/praise surrounding them. Nickelback were still huge. Electropop was on the charts, but it wasn't fully fleshed out yet. Post-grunge, emo, r&b and dance-pop were the most popular genres in music. 

Technology wise, most people still owned flip phones or standard Nokias. I remember as I can recall when my Mum was looking through the catalogues for a new phone at the time and I suggested to her that she should buy a flip-phone (as they were still the 'most trendy' looking phone). People still recorded shows onto VHS. Blu-rays were around, but they were incredibly expensive. Sanity used to sell them for between $30-$35 each. Many families still went out to video rental stores on a Friday or Saturday night to rent out a few movies for the weekend. LCD and Plasma TVs were taking off in popularity, however many still owned analogue TVs as well. Foxtel used to air commercials which promoted shows now being in widescreen (or HD). Internet wise, most people were still on broadband or even dial-up. It was frustrating for me at the time as the Wii that I received for Christmas was set-up in our lounge-room, but I couldn't use any of the internet features on it as the modem was in another room in the house and we would have needed a cable to connect the Wii to it. People used digital cameras to take photos, or if you were out of touch with technology like my grandparents, film cameras. Facebook was on par with Myspace in terms of popularity. Blackberries were around, but they hadn't yet reached their peak.

In terms of fashion and clothing styles, spiky hair was still trendy. A lot of the other boys in my grade had it. My hairdresser and Mum would try to convince me each time I got my haircut to put gel in my hair and get my hair spiked, but I always refused. Baggy jeans and long cargo pants were also still popular, though they weren't as commonly spotted as they were during the mid 2000s. I can't remember skinny jeans being around back then at all. I mostly just wore board shorts or tracksuit-pants. A lot of kids still liked to wear their caps backwards. I'm obviously not as well knowledgeable on girls fashion trends, but just based on looking through my old family and school photos from the era, those Late 2000s-style vests were also still popular back then.

Looking back, it was still very much a '00s cultural era and that's personally how I've always remembered it. There were of course emerging 2010s trends coexisting with the trends and aesthetics of the mid-late 2000s, but the overall zeitgeist of the second-half of 2008 and the first-half of 2009 still lent towards the noughties.  

BlackBerry is generally thought of as more of a 2000s thing than a 2010s thing, so even if we were at the peak (which was 2009-2010), it would still make the era feel 2000s. When people think "2010s", they think of iPhones and Androids, plain and simple.
And that in my opinion is a big thing to consider. Whilst Android first came out in this time, it wasn't popular yet and definitely still in its infancy. For fucks sake, the first version of Android didn't even have a virtual keyboard, meaning early Android phones from 2008-2009 were keyboard phones much like the BlackBerry. As for the iPhone, it was starting to gain popularity but not ubiquitous yet. Cell phones were in a transitional period. Smartphones were just starting to really take off, but many of them barring the iPhone felt rather primitive, with slow, unresponsive UIs, and a general sense of "newness" you really did not see anymore from about 2010-2011 onwards. Many were either keyboard phones or T9-style phones like what dominated the 2000s. Meanwhile, flip phones were still fairly common even if they weren't the new trendy thing anymore, many people still had them.
And in terms of TVs, I'd say by this point, we were firmly in the LCD era AT LEAST when it came to new TVs being sold. Some people still held on to their CRTs that were still working that they bought in the early-mid 2000s. Even still, there are things that make TVs not quite feel 2010s either. The big thing for me is that smart TVs were hardly a thing at all at this time. In fact, they didn't really start to take off until around 2012. Another thing to point out was the analog-digital TV transition. This was actually supposed to happen in February 2009, but it was delayed until Summer 2009. Still this was the very last era to have analog TV broadcasts, which I think is significant.
Home video during this time is another thing to consider. This is when Blu-Ray started taking off after defeating HD DVD in the format war, however, many, including myself, still owned regular ol' DVD players during this time. This was actually one of the things that allowed the PS3 to start to take off during this time, as many bought the PS3 to function as a Blu-Ray player in much the same vein they did with the PS2.
Ultimately, this was a transitional period between the core 2000s and oncoming 2010s culture. I do not consider 2008 or 2009 core 2000s at all, but culturally, 2008 is definitely a 2000s year in my opinion, whilst 2009 and 2010 are essentially a hybrid between the 2000s and 2010s.

2009 musically was far more 00s than it was 10s. I remember hearing this song back in late 2009. Didn't sound remotely 10s then and now it's even more obvious how 00s it sounds.