I'm not enough of either a graphic designer or web dude to understand the finer points of the two company's product lines, but these guys do:
- What Do I Know?: Adobe Buys Macromedia.
- Mezzoblue: Macrodobia.
- Veerle's blog: Macromedia and Adobe Join Forces!.
Quick sum-up: Adobe is print, Macromedia is web. Lots of fear about favorites in the overlap being left to die. Competition with Microsoft is probably a big factor.