and beyond that there are open source engines for things like physics (fisix, box2D, APE, etc, etc, etc...)
or even 3D engines for flash (papervision3D, away3D, sandy, etc, etc, etc...)

i think open source code and lots of available engines help flash developers work more on the creative aspects of programming,
then the "under the hood" technical stuff. but i suppose that's true of most languages.

i checked out a lot of the alternatives people gave and they all look good and useful, but some felt a little daunting... processing in particular ;F i guess i prefer the whole suite that comes with flash to the small utilities that are essentially text editors and need to get more confident with tough programming - what puts me off isn't programming logic but the abstractness of looking at the text instead of the end result. flash still seems most comfortable to me because i remember using games factory years ago, and it's not so very far away in some respects.

If you want something usable by many now and for a few years, go with flash.  If you want to be progressive, though not all browsers support it yet (internet explorer of course), go with HTML 5.

regardless of html5, Flash will always still be around for in terms of ActionScript and the Animation platform it has. I fail to see a site like http://newgrounds.com spawning up which is basically the same except for html5 content.

But to be honest. for video and audio html5 will replace Flash.

TL;DR: flash is going to stay for a LOOOONG time

It should be noted that Flash has a lot of serious problems even today. Lack of support for hardware acceleration, low accuracy of all the timers (and even worse, different accuracy for different browsers), different speed depending from the browser and how it is embedded (up to 50% slowdown in some situations!), rather underdeveloped sound capabilites (good luck with seamless loop of MP3; peak CPU overhead at start of every sound) - it just a few that come in mind first. Well, alternatives nowhere near by popularity, and has their own problems too.

i have to agree w/ some of these comments.

the lack of hardware acceleration is sad really. but the problem isnt adobe. they are trying hard to work w/ gfx card developers
to create a standard method of accessing the GPU from flash. but ATI and nVidea dont ever want to work together on anything.

the timer issue is a big one. but that problem is intrinsic to the browser running it.
IE handles things one way, firefox another, chrome yet another... since IEEE will not create a standard for such things,
this becomes a problem w/ almost every run-time plugin (e.g. silverlight).

creating sounds from nothing in flash is not easy (though not impossible),
but i hate that looping mp3 argument. it's litterally 2 lines of code...

var soundLoop:Sound = new LoopingSound();
soundLoop.play(0, int.MAX_VALUE);

done.

this is an argument as old as the player itself.
i liken it to: mac vs pc, windows vs linux, nintendo vs sega, etc...

but i digress...
to answer your original question, i think if you want to program
web-based games, that are awesome. unity3D is your plug-in of choice.

as for developing flash, you actually have a lot of options.
the "flash creative suite" is obviously the first choice. it's the native flash IDE that adobe has developed.
it's expensive. your 2nd choice is "flash builder" (aka flex builder). this is adobe's new IDE that's focused
more on code then visuals. it's my preferred development platform. it's built on eclipse, so there's tons
of cool coding features like strong typing, code hinting, intelesence, auto function writing, proto-classing,
etc, etc... this is also pay ware, but it's much cheaper. next up is "flash develop". this is an open source *FREEWARE*
application, similar to flex, for developing flash content. it's really fast and really lightweight. it uses adobe's
real open-source SDK (same as flex), so your exporting real flash.

html 5 is still in it's infancy (the standard still isn't 100% yet). but it's growing fast.
if you haven't seen them, check out the chrome experiments. good stuff.

it exists already... check out smokescreen
take that steve jobs!!!

flash is here to stay!
whether yew like it or not!
lulz ;D

Well, it be fair it was pretty cool when I used VideoWorks on a Mac SE in like 1987...

Also, HTML5 is supposedly not going to be completely ready until 2022, so I think Flash has quite a bit of life left in it. And there's already a few open source Flash players about, so maybe by the deep dark post-apocalyptic future of 2022 there will be a Flash player written in HTML5!

That long? Not if apple keeps up like they are. Youtube and vimeo have already began to switch and almost everything is available inn html5.

But an HTML5 flash player would be cool.

Flash is on it's way out thanks to apple. I do think HTML5 is the next big standard. If you just want to make a small game flash will be the way to go unless you plan on using it for the next few years

But if im not mistaken html5 has a free open programming environment so no need to pay for dev tools and such.

I'm not so sure about HTML5 replacing Flash for games. For example, no game with an online high-scores chart will work if everyone who plays the game can view and edit the source code with a couple of clicks!

Also, HTML5 is supposedly not going to be completely ready until 2022, so I think Flash has quite a bit of life left in it. And there's already a few open source Flash players about, so maybe by the deep dark post-apocalyptic future of 2022 there will be a Flash player written in HTML5!

But if im not mistaken html5 has a free open programming environment so no need to pay for dev tools and such.