Yes, but that only shifts the image left/center/right and fails to grant the advantage of <img src="blah.gif" align="left" /> (allowing text to wrap around and float next to images).
Better late than never? I swear I found this custom bbcode around here somewhere, but can't find it again:
Code:
Title: Float
Tag: float
Replacement: <span style="float:{option}">{param}</span>
Example: [float=right][img]Image[/img][/float]Float Text
Description: Float an image to the left or right of a block of text.
Use {option}: Yes