I haven't heard the rumors, though they seem to launch things (photoshop, lightroom, camera raw, etc.) a lot on February 19th or in mid-April.
I don't know how much correlation that has with their other products, though since they're sort of product "Suite" oriented with a lot of things (less so with Acrobat) I'd think they'd announce updates mostly all at once.
I'd suspect they'll either do it by the start of May or maybe not at all in 2008.
There's been some rumor about a new Photoshop possibly coming out sooner than expected, probably because they dropped the ball badly on 64 bit support for CS3.
Acrobat? I'm no expert but I can't think of much reason why they'd be making major changes to it this year .... I guess PDF got standardized as an international standard recently... so I suppose there could be some minor updates in relation to that and 64 bit platforms.
Try asking on a more desktop publishing / Macintosh / Adobe oriented board for people with more access to good rumors.