The Compose music tablet is a design concept, by Ouyang Xi, He Binbin, Zeng Li & Li Bo, intended to provide a mobile composition solution.
The pen acts as a mic that you sing into. When docked into the digital paper tablet, your vocal harmonies are automatically transcribed from the recording in the pen into a [...]

ScoreRender is a Wordpress plugin for rendering sheet music fragments into images. It supports converting fragments in excerpts, posts, pages and (optionally) comments.
Currently it supports 4 music notations: ABC, Guido, Lilypond, Mup.
For latest version, detailed usage instructions and demo cases, visit the ScoreRender site.

The International Music Score Library Project is a cool site that lets you download public domain music scores for free:
MSLP attempts to create a virtual library containing all public domain musical scores, as well as scores from composers who are willing to share their music with the world without charge. You can read the full [...]

2008 Summer NAMM Show: Sibelius announced Sibelius First, a new notation and composition tool for singer/songwriters, keyboard players and guitarists. 
“Sibelius First is that great first step into the world of professional score writing for aspiring composers,” said Jeremy Silver, Sibelius Software’s managing director. “If you’re more comfortable composing while playing a guitar or a keyboard, then [...]

At the 2007 Summer NAMM Show, Notion Music introduced Progression, a new sequencer, tablature and playback application designed for guitar players.
Description:
Progression is designed to be a powerful, yet easy-to-use guitar application for creating, learning, and distributing music. Guitar tablature or standard notation can be entered with a keyboard and mouse, or played into the program [...]

MakeMusic has unveiled Finale 2008. According to the company, the latest upgrade offers “unprecedented playback options, major productivity enhancements and even more control for the perfect page.””The missing feature in notation software is the ability to add an audio track,” stated John Paulson, chief executive officer of MakeMusic, Inc. “By adding this audio feature in [...]

Notation Musician 2.0 and Composer 2.0 offer casual musicians new ways to music - both sheet music and audio:

Start with music you find on the Internet (tens of thousands of free MIDI files).
Customize and arrange the music to fit your or your group’s particular needs -fake book lead sheets, custom parts (which stay connected with [...]

2007 Winter NAMM Show: Notion Music announced version 1.6 of Notion, their flagship music composition and performance software. The update adds new scoring features, improves file handling, adds support for lyrics, and expands Notion’s capabilities beyond classical music genres.

Among the new scoring features in Notion 1.6 are support for lyrics, chord symbol entry and playback, [...]

MakeMusic announced today the release of Finale SongWriter 2007, a new version of their entry-level music notation software. SongWriter lets users compose and arrange music, hear their work and print sheet music. This latest version runs natively on both Intel- and PowerPC-based Macintosh as well as Windows computers.
Notes can be entered via a computer keyboard, [...]

eMedia’s Guitar Pro 5.1 is the new Windows/Macintosh hybrid version of the best-selling multi-track tablature editor software for guitar, banjo and bass from Arobas Music. Besides writing scores, Guitar Pro 5.1 is a tool for beginner and accomplished guitarists alike to improve, compose, or accompany themselves.
New advanced notation features add drum notation, vocal notation and [...]