Plain text format -- SVG files can be read and modified by a range of tools, and are usually much smaller and more compressible than comparable JPEG or GIF images.

Scalable -- Unlike bitmapped GIF and JPEG formats, SVG is a vector format, which means SVG images can be printed with high quality at any resolution, without the staircase effects you see when printing bitmapped images.

Zoomable -- You can zoom in on any portion of an SVG image and not see any degradation.

Searchable and selectable text -- Unlike in bitmapped images, text in SVG text is selectable and searchable. For example, you can search for specific text strings, like city names in a map.

Scripting and animation -- SVG enables dynamic and interactive graphics - such as the Flashâ„¢ graphics we are familiar with these days.

Open standard -- SVG is an open recommendation developed by a cross-industry consortium. Unlike some other graphics formats, SVG is not proprietary.  However there might be patent (read: royalty) battles soon, so keep that in mind!

True XML -- As an XML grammar, SVG offers all the advantages of XML!

It's a 2D (not 3D) graphics solution at this time

SVG offers anti-aliased rendering, pattern and gradient fills, sophisticated filter-effects, clipping to arbitrary paths, text and animations.

SVG (unlike Flash) is a W3 recommendation

It is explicitly designed to work with other XML technologies such as CSS, DOM and SMIL

Mozilla already renders SVG natively!!  For most other browsers you will have to download and use a plugin (Adobe has one for example)